At least in the situations I've seen the salespeople made effective use of FUD and ego massage on less technical managers.

It wouldnt be nearly as effective though, if they werent playing the long game and if the products they sold didnt each function to increase the vendor lockin one step at a time.

There ought to be good money decoupling corporate IT systems from these systems but weirdly nobody seems to care that much about IT spend on preferred vendors.