Any company blacklisting AGPL is going to be blacklisting GPL as well, which would preclude using git as well (even the more permissive libgit2 is just GPL with a linking exception).
The thing they worry about is deciding what falls under AGPL. With GPL it is easy, if an executable leaves the building, source goes with it. With AGPL, when almost very thing is web connected, it can be hard to draw the line on what you have to open source (or just tell people you are using.. do I have to add every AGPL program in an Ubuntu server install, just in case one is getting used by something else?)
Whether rightly or not, https://www.theregister.co.uk/2011/03/31/google_on_open_sour... and other writings on the topic had a big impact on enterprise adoption of AGPL software.
There's also the fact that most prominent AGPL licensing tends to be around commercially backed software where the main backer owns all the source and is therefore in position to not hold themselves to the same standard of sharing changes as their customers and third parties must do.