If they provide less than ideal for you, then you leave. Providing less than ideal is less than ideal for them, unless they don't care about losing you, in which case you probably don't want to be there anyway.

Out of the four jobs which I have voluntarily chosen to leave, three of my four resignations were because the employer stopped giving me meaningful work that prevented skill atrophy in my primary areas.

Preventing this skill atrophy on my own time, such as with side projects, is (a) ridiculous and (b) a physical impossibility because of the burden of working hours and exhaustion demanded by the employers I had at the time.

It's absolutely unreasonable to say that someone must find a way, outside of work hours, to effectively perform an entire second job's worth of practice and development, because their job isn't giving them work that exercises them.

It's like hiring a super model, asking him or her to sit on a sofa eating candy bars all day as the work you are paying them for, but then telling them to use their personal time to remain fit for supermodeling. It's a patently absurd idea.

You're free to say the words "developers should take control of their own career development" if you want to, it's just absurd. I mean, in once sense of course you're in control. Even if the career development happens at work, it's you doing it, so you (by definition) are in control.

But you aren't just saying "you're in control" in the obvious, tautological sense. You're going further to say that you should place no expectations whatsoever upon your employer to match up real-world business items to your skill set in any way that is related to appropriateness or which factors in your goals. That's the absurd part. You're saying "don't expect your manager to actually manage anything ... just resign yourself to the idea that they will randomly throw undifferentiated business concerns at you like a dartboard."

Real management acts as a double-sided adapter, with bespoke, unpleasant business realities on one side, and well-fitting tasks that are matched up to employees on the other side. Converting bespoke, unpleasant business needs into appropriate, on-topic tasks for specialized employees is managing. Saying an employee shouldn't care about this, to me, is among the worst advice I can think of. This should be one of the primary things any employee cares about.

Because the one thing that absolutely won't happen, simply by physical limits of exhaustion and life responsibilities, is for you to personally cultivate or exercise those skills during non-work time. Yeah, maybe you can read a tech book here and there. Maybe you go to a conference. Maybe you occasionally do some open-source work. And all of that put together amounts to maybe 5% of what's actually necessary to stay sharp and competitive in the employment market.

Instead, you absolutely should hold the employer accountable. They are asking you to bear an insane opportunity cost of lost time whenever you're working for them -- so much lost time in fact that if that time is not actively dedicated to building competitive skills, you will quickly become unemployable and you'll be so atrophied that you'll have no option but to stay at that employer because no one else will want the shell-of-a-former-expert your current job will have morphed you into.

There are a lot of good reasons to quit a job. You might not be paid the amount you prefer. You might not receive benefits that enable the life you prefer. And you might not be asked to perform tasks that cause you grow in skill, solve challenges, or learn new things in the way you prefer.

For me, these are not tradeoff-able. An employer either satisfies all of them adequately, or else it's not really an employer but just a thing wasting my time that I quit from.