You are fortunate to have worked in mostly good places! I have seen a lot of sales compensated on commission at contract close. It gets as dysfunctional as one would expect.

I still don't agree it's easier, though. If a customer stays, is it because they've received great support or because the salesperson found a good fit?

What I'm trying to say is "if sales get compensated when a customer sticks around, then so should everyone else supporting that customer".

Basically the only good incentive programme is profit sharing (or ownership) applied across the organisation.