Self written personal packages are like re-inventing the wheel. Ok, there is only one exception with LXQt - when we started to put LXQt into Debian we took my personal packages as starting point for the sprint in Heidelberg at Debconf 15
Reason: They were complete and based on git - the last released things was older than a year and based on Qt 4 instead of Qt 5.
If we talk about personalized packages based on the official ones i’m with you. But don’t underestimate the introduced bugs if starting from the scratch - file conflicts, missed or plain wrong dependencies and recommends included.
Using the “official” packages as starting point make sense for another reason: If one do those things longterm one will be able to jump in as a maintainer for the distribution of choice if one want to - and that can be a good thing.