Yes, as long as the thing to fix is in the open source component, which often is not the case. Also there is a serious overall lack of documentation in the Mer/Nemo/Sailfish land and random parts being closed does not really help with tracking down issues as you basically stumble on black boxes left and right.

The other difference is that Sailfish OS is a quite complete and overall working system while Nemo is basically a bunch of middleware (the same Sailfish OS makes use off) but without most of the actual user facing bits (all system level GUI elements, core apps) + some minor stuff salvaged from the MeeGo era.

So one is unusable until you spend huge resources to basically rewrite all the closed bits (this might sound familiar to some people...) while the other is kinda useable but fundamental pieces are closed and can't be fixed and improved by the community.

Actually I think we would get significant amount of contributions as there would finally be something that is both in usable shape and fully open source.

It is much easier & much more motivating to fix & improve something you and others can actually use day-to-day rather than hacking on something for years without visible results.

I think the N900 and its community are good example of this - even though still hindered by closed parts, it is a device & platform that is quite open & day-to-day usable, which is IMHO why it has spawned such a considerable & durable community that is still writing apps, improving & supporting the platform to this day, long after the N900 has been officially discontinue and all official support dropped.