I’ve been a DM for many years, and in all that time I’ve had maybe three players read the PHB. I don’t mind explaining the rules, but it would be nice to not have to remind the wizard how spell slots work (again). Is this a common thing for most groups?
For a quick one-shot to test out the system, most of my players will just skim the rules, and that’ll be enough. But if I run a long-term campaign I expect my players to have a basic grasp of the rules, but most importantly know how their characters rules works.
I will happily explain and help players get started. But if they ask me for 100th time which die to roll; don’t know how their character works; or similar basic things, I will get pissed at some point and ask them to please learn the game we’re playing.
You don’t need to know every single rule, but a basic grasp of them is just the bare minimum or I will kick them out of the game at some point. This hasn’t happened to me yet, all my players are very good at picking up new systems.