I wouldn't say SharePoint sucks. It sucks when you don't use it as intended. The GP was using it as a file share. SharePoint is very good as a light document management solution with MS Office integration.
As far as the rest, I said the comparison is to Documentum. Documentum generally recommends an implementation team. It is not uncommon that Documentum has a permanent IT support department (i.e. multiple people). Share Point can get by with less than 1. As for metadata and using it its way. Yes. That's standard for a document management solution.
Imagine if someone was talking about SQLServer as a replacement for Oracle and we were discussing the lower cost and lower administrative hassle relative to Oracle. And you kept coming back with a comparison to using text files and how much easier and less of a problem text files were. SQL Server did a great job of taking Oracle administration (a skilled profession) and making it something that a moderately skilled admin could do part time on the side. Similarly SharePoint gets you 80% of Documentum for 20% of the cost.
1000 users on Documentum fully configured is probably just under $1m.
1000 uses on Sharepoint fully configured is about $200k
1000 users on a fileserver fully configured is going to be $20k.
That's where you need to make the comparison. For smaller business, SharePoint online you can be at $7 / user / mo for a small business. There is nothing remotely like that for the higher end suites. But heck I can get 50g file share in the cloud for free.