For me it's just a question of where I would want to invest my org's time.

For example: how much time do I want us to spend looking after a task/ticketing system? About zero. How much time do I want my org to invest in DR planning for our self-hosted wiki? About zero.

So unless there's a convincing difference (cost, features, etc), cloud-hosted SaaS would be my choice there.

The answers also probably change a lot based on how the company operates. Would I have been comfortable with a self-hosted wiki when I worked at Facebook and we had a pretty damn good team providing DBs as a service? Yes. Would I have wanted to do the same when I was the sole infra person in my group at another job? No.

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.