Or create the demand for an index/curation platform/search engine, which would be something quite interesting, I think.

Google had one but they shut it down.

"Back in the old days" we had Freshmeat...

gitlab.com is a fine compromise, albeit I'm not a fan of their "private repos for free" model, it means a lot of software that might have utility if it were default-open will be lost behind default-privte repositories.

But if gitlab jumps the shark like github is doing we can always have anyone in the ecosystem selfhost a clone, albeit we would need to reimplement all the enterprise features people want.

In my experience it was the other way around. I signed up with gitlab only because they offer free private repos. Now since I already have an account with them and I don't have to go through the hassle of setting up stuff again, I'm only a couple clicks away from putting some project in the open.

Self hosted solutions lend themselves towards being freely indexable via search engines, many of which are optimized towards source code repositories.

Like the move to self-hosted websites made finding websites harder? /s