I see two things that are important: consistency, and communication. The game world must be consistent with itself. The DM and players must communicate with each other how it works.
Lore is simply a method of achieving consistency and communication. It gives players and DM a consistent backbone to built their game upon. Using a shared lore allows the consistency to be communicated through the group without all details being directly discussed.
PC options must be communicated between players and DM, and must not break the consistency of the game world. If a player wants a new option it is their responsibility communicate with the group, and ensure consistency is maintained. In that sense, going against "lore" is fine as long as the whole group is on the same page. At the same time "you can't do that, it goes against established lore" can be an efficient shorthand way of saying "we have a well defined, mutually agreed upon, and consistent world that we all play in, and what you're doing breaks those social contracts".
Lore is simply a method of achieving consistency and communication. It gives players and DM a consistent backbone to built their game upon. Using a shared lore allows the consistency to be communicated through the group without all details being directly discussed.
PC options must be communicated between players and DM, and must not break the consistency of the game world. If a player wants a new option it is their responsibility communicate with the group, and ensure consistency is maintained. In that sense, going against "lore" is fine as long as the whole group is on the same page. At the same time "you can't do that, it goes against established lore" can be an efficient shorthand way of saying "we have a well defined, mutually agreed upon, and consistent world that we all play in, and what you're doing breaks those social contracts".