I think it's likely the real life phenomenon of a global accruing of knowledge where once someone does something the speed at which a second, third, fourth person etc doing the same just continues to increase. Clearly the information is out there and multiple pirates know about it so could be like how in real life once a NY Times Crossword is out there, people who days later hadn't seen it will on average still solve it faster (this is a known phenomena). I do agree with all of your points but am doubtful we will get any explanation from Oda on the matter, hence why I'm trying some plausible info.
Even in the Kaido example you gave, I'm like so what to Kaido going to Lodestar since he can't read the info. Both him & BM seemed to want to take Robin too since they need someone to read the RP. Oda has completely left us with a big question mark when it comes to Poneglyph knowledge and how any pirates outside of Roger & his crew (thanks to VOAT) know anything. At this point its kind of manga magic or plug-in any plausible scenario you can think of as a reader.
On the Rocks example, I also think its important to note that he had some ideas about Poneglyph but nothing close to Roger.
Lodestar is not implied to be requiring ability to read the Ancient Language since that is where people go to learn about Poneglyphs and things related in the first place.
Lodestar is where people have to go before they can initiate their journey to Laughtale at all.
Furthermore, when Roger went to Lodestar for the first time, he also couldn't read the Poneglyphs, so there's no reason why Kaido shouldn't be able to acquire the knowledge if he did venture there.
Big Mom unlike Kaido was a veteran, she was one of Rock's commanders, so it makes sense that herself and Shiki were well aware of their importance. In fact, Roger went to WCI to steal her Poneglyph, she had one, so she was probably clued up from Rocks whom the WG said was breaking taboos usually meaning reading poneglyphs.
Shiki asked Roger to use the Ancient Weapon and subordinate himself to him.
Kaido despite being in Wano by sheer luck didn't know he had to interrogate the samurai when Oden was alive, otherwise he would never have waited 20 years to interrogate the Samurai, he'd have done so there and then which implies he only learnt this knowledge recently and thus realised the value of Oden's retainer in wake of Oden's death.
Rock's name was even cleansed from records implying he knew a lot, anything the WG covers up is heavily related to the Poneglyphs and Ancient Kingdom.
He must have had similar knowledge to Roger except for the fact he never went to Laughtale or had the resources/luck, he likely also went to Lodestar.
Big Mom said, she didn't want other people to know the significance of Poneglyph too, otherwise the competition increases which is why Big Mom cursed Roger for starting the Pirate age - this was likely the mentality shared by many pirates other than Roger at the end of his voyage. This explains why Kaido only learnt so late about Poneglyphs, a treasure he'd been sitting on in Wano ignorantly.
Adds more credence to the idea this knowledge is select even amongst the highest level of Pirates. An Emperor like Kaido only learnt about this knowledge recently despite being fully involved in the underworld and it seemingly took Lodestar to begin his true voyage to being Pirate King.
On the Rocks example, I also think its important to note that he had some ideas about Poneglyph but nothing close to Roger. Rocks didn't go and get the RP and find the Rio Poneglpyh. And fact is that Roger didn't even go on that final voyage until decade+ from the Rocks incident. This leaves me to believe Rocks only found some random poneglyphs (not RP) and starting digging into info without ever discovering anything significant. Otherwise can't really explain why Roger would wait so long to do the final voyage (maybe more manga magic?).
If anything, Roger not going after a decade
only serves to imply it's just that difficult to get information. It took him a decade to get any progress in his journey.
He only had the luck of meeting Oden 13 years after Lodestar, so it makes sense he couldn't advance in his journey. It's not that he waited.
Roger knew he needed Road Poneglyphs, he just couldn't get them without Oden, and that's probably the situation that Rocks was in. He knew what he needed, but was unable to acquire them because he lacked luck.
My point being Luffy just has stupid luck, he runs into every thing he needs because of Protagonist privilleges. It makes no sense that Kid just happened to come upon this knowledge.
He's not exactly Big Mom who was a subordinate of Rocks who was actively seeking Ponegylphs as a top tier commander meaning she was likely well informed and given high levels of responsibility. He's not related to an archaeologist. He's not anyone significant to just know he needs Poneglyphs and Road Ones at that.
It's just strange that Kid has knowledge of something impossible to acquire without the right connections. Either he went to Lodestar or maybe there's more to kid than we know.
(iirc Kid lost to Snack, but Urouge defeated Snack and lost to Cracker.) Urouge has a higher chance of having heard about poneglyphs early than most of his generation since he's from a sky island and those don't seem to be under the kind of scrutiny that the WG has on surface islands.
