I've worked on to many long dead projects with scant doco and the best ones are always where people colored inside the lines. Remember google web toolkit? That flamed out hard 15? years ago.
I've recently had to make a mod to a decaying app written in GWT. It was easy because no one got creative. I think theres a long term risk with rolling you're own that you box yourself into a lot of corners without knowing it.
You can also get really creative with frameworks, specially if you need to quickly overcome some strange limitations imposed by framework. There is also a long term risk with using frameworks - somebody here mentioned method renames in Laravel, that makes upgrading difficult.
Im not talking about writing your own http server, or building the whole database access library. You can use some ready made libraries. As long as you keep proper boundaries between IO and business logic, you can fairly easy change the IO libraries.
Of course there is quite some overhead there, and for some projects it makes not sense.
I've recently had to make a mod to a decaying app written in GWT. It was easy because no one got creative. I think theres a long term risk with rolling you're own that you box yourself into a lot of corners without knowing it.