Huh...I think what you describe more accurately represents the perk system rather than learn by doing.
Cut grass. Earn currency. Shop for desirables.
Play game. Earn skill points. Shop for perks.
heh

true, not a great example of learn by doing. It was my poorly worded attempt to trigger the idea that the things we 'earn' for ourselves are usually more valued than those simply 'given' to us.
And yes, at the core of it there aren't any 'freebies' in the perk system, we're all still 'earning' every point we recieve, however we might choose to spend them, they were earned.
Could be argued that simply finding a magic book & shazzam, now you can make a Minibike, is fairly silly, yet it follows the general idea of 'learning' that we're all used to; have a goal, make an effort, "study/read-a-book", learn how.
Going to the gym to get stronger, eating healthier to feel better & have more energy, training for a 10km fun run by, well, running.
Even though it's pixels on a screen those are easy to equate to and, likely, feel more 'right' or 'natural'.
However, those are the easy ones. While I might like a system where we could wrench multiple cars and gradually learned how they worked, resulting in unlocking how to fix up a wreck to a drivable state, others may not, or the time required to put in is too high.
So, maybe, to me, a mix of both would feel better. So what?, it's TFPs game & they clearly didn't like the old system.
I'll concede that in the end it's all silly, and very,
very subjective, which is mainly why I've stayed away from this whole area.