Earlier quoted context omitted.
I'm not sure what exactly you're reading in my words, but I don't really understand why you think it's my "effing job" to provide training for inexperienced developers. My contract stipulates no such thing, and despite what you seem to assume, I have been in fact hired to find solutions, and write code. It's a little disconcerting to see someone make such self assured inferences about me, based on a single comment.
when i hire someone, their job is to do whatever it takes that is in their capacity to move the project forward. if it takes a larger team, then getting new team members up to speed is part of that. and if that new team member is unfamiliar with the frameworks the team is using then training them on that is part of the job too.
How about you encourage the team to actively monitor where onboarding takes time, year by year, learn from that, make onboarding materials which encompass institutional knowledge, and make the process as much self serve as possible?
Or assigning a "buddy/mentor" like persona that is responsible for this specific onboarding, so the rest of the team don't get distracted + the expectations on delivery are lowered for the "buddy"?
> it takes that is in their capacity to move the project forward
It takes quiet and uninterrupted work and focus time, and spending effort on making onboarding as smooth as possible. Just hoping your devs will do all the work of onboarding + their own work, and you doing nothing, that's just...what I expected I guess.