Or would it be worse as it wouldn’t have the broader knowledge to understand the reason you’re coding what you are anyway, understand the logs and iterate?
Coding an exercise app will benefit from a model that can code and understands what exercise is. A car showroom website will benefit from a model that understands what relevant filters would be.
Of course there are synergies between different fields. I'm not saying cutting everything off as close as possible to it's purpose must be the best way. But that's a long way from a single generalized model.