Earlier quoted context omitted.
> I had a manager at a startup tell me that conventional management assumes that engineers will only stay at a company for 18 months, so they really pile on the stress which is ironic, because isn’t that why people stay less and less longer at a company (can’t stand the slog)?
I think economically it may make sense to hire fresh people for less money, burn them out and then have them leave soon. This may be one reason for ageism .
If the job is focused on smashing rocks with a hammer to make smaller rocks, that's probably true.