I think this is partially due to the informality that many GitHub users tend to have with respect to managing their projects.
It's rare to see a GitHub-hosted project that offers proper releases, proper planning for those releases, proper documentation, and the organization and project management efforts that enable such things.
The lack of such basic project management structure leads to projects that see very erratic development, or outright abandonment. Many GitHub-hosted projects are barely more than a hobby, rather than an ongoing concern. Their code may be somewhat usable, but it's rarely comparable to what we see from more organized projects.
Proper release planning for tiny one man fifteen users project is very little planing.
Those projects do not get erratic development or get abandoned because they lack "proper planing". That is reversing cause and effect. They lack heavy planing because their development depends too much on free time of one or two people, who have other life priorities. No amount of planning will change that.
I don't see that as a bad thing. Mostly it seems to be a reflection of how low the barrier to entry is on github. It's easy to get up and running there, so naturally lots of people do, even if it's just a hobby project they work on once a year during Christmas break....
It's rare to see a GitHub-hosted project that offers proper releases, proper planning for those releases, proper documentation, and the organization and project management efforts that enable such things.
The lack of such basic project management structure leads to projects that see very erratic development, or outright abandonment. Many GitHub-hosted projects are barely more than a hobby, rather than an ongoing concern. Their code may be somewhat usable, but it's rarely comparable to what we see from more organized projects.