Do you have a source about followers that may be companions ? I don't really remember about it.
Anyway temporary followers is not really the same as companions. As many players, I like management and a party of 6 instead of 4 is 150% more management
I think they talked about it very briefly in the first live stream of the game. I remember noticing that and discussing it with some folks either here or on Reddit, and people pointed out the mention of followers which would be temporary additions to the party.
Unfortunately, I can't find the exact source, though I did find some other people having the same impressions. I could be wrong in some capacity - maybe paople fight with you, but you don't have direct control over them. Some interesting screens I run across but I don't know if they are relevant to the discussion.
First one might be just summons or familiars and such, but second one has a 5th dude in the party. It could be just the Warlock guy and Larian experimenting with 5 men party though.