[mirabilos]

Yes, that’s actually what GitHub and I are talking about now.

Any OSS licence already grants way enough rights for a hosting platform to operate, period. Anything else can be solved technically and does not need to involve legalities. (For example, when displaying search result snippets, put notices pointing to the original file in the original repository, as “context, complete copyright notices, licence and attributions” right next to each.)

So the ToS simply need to require all those grants only for works that are not under an OSS licence (see also my updated article, remember http://www.mirbsd.org/permalinks/wlog-10_e20170301-tg.htm is the correct link, NOT the one on top). For any works NOT under such an OSS (Open Knowledge, Free Cultural Work, whatever) licence, the ToS grant is not unjustified to ask (especially as GitHub doesn’t care about hosting OSS projects, or the licences of whatever content they host).