How to put this- I see the merit in your suggestion, but it's also ignoring the disadvantage. That being- protectors tying down themselves to one person, thus pretty much negating their use. Part of being a protector is anticipating a kill and saving someone. Your suggestion not only forces them to lazily restrict themselves, but they also pretty much make themselves redundant? And although I didn't mean for roles to go around intentionally popping illusions, I also see benefit in illusions going regardless. Because it's just much more overhead that even the said player is unsure of.
Tl;DR- protectors might as well just do their shit. I doubt even by D3/D4 there would be a solid enough reason for a protector to stick to one person cos they're sure said person is town.
You are missing my statements on changing the target depending on reveals or new info, or losing faith in that said person is town. You literally cannot anticipate kills with many parties, especially with the low info amount we currently have. It's a wasted effort. You may call it lazy, but the truth is that it's a very valid way to go
during this current time where too much is unclear. You cannot anticipate anything here, hell you cannot even anticipate which one of the people you did not protect N1 are still alive. All you'd know in this case is that one N1 target that is living. If you trust he is town, protecting him forever is 100% the way to go until more is known, and even then could be a valid use.
And you keep ignoring how, in mafia's eyes, whether 1 person is always protected or always someone else anticipated, there is always a person that can't be killed due to Doc and they do not know who that is. D2 is shaping up to be similar to D1, so with lack of news this play is the right one.
But let's stop at this as it leads nowhere, and you're just hurting your credibility in my eyes atm honestly.