I think some time investment is very sensible for any form of decision about infrastructure. Today we have companies complaining about their software dependence, software license costs have heavily increased.

Also, an experienced admin can setup a repository server in a day. This is probably even less time investment than getting offers for solutions. In my opinion the maintenance amount isn't less with SaaS at all as most maintenance work is integrating data.

We do have a self-hosted wiki. We don't even need to think about it if we want to integrate document search or analysis. We own our data completely here and I would argue that data is quite an important chunk of wealth for a company. Some SaaS companies know that as well and they basically take your data hostage. And as a plus, as many things are on a local network, any access to that data is pretty much instant.

To save time on infrastructure decision overall is a mistake in my opinion. You wouldn't do that for your ERP or CRM solutions either.