You think Microsoft losing GitHub repos is more likely than poor bastards trying to make sense of the git command line? You think these guys are going to do a worse job with their centralized service?
People have lost data on GitHub from repositories being copyright striked for example.
At least with git, every developer has a copy of the full history so full data loss is impossible really. What happens if this company folds? You're left with some proprietary repo that you suddenly have to workout how to self host.
It just doesn't make sense when compared to just learning git which is definitely the most fruitful thing a developer could learn at the start of their career.
