Specifically, they pay for the cronyism aspect of the service. They pay because they're friends with the founder (or the decision-maker expects kickbacks now or in the future or at the very least; they share the same VC and are doing someone a favor), not because they need the features of the software. The features are only there to provide narrative support (I.e. justification for the money being paid). You can see that this is the case when the software gets really bad and there exist free open source solutions, the company has self-hosting capacity, but the company keeps using the expensive, clunky SaaS solution founded by their buddies... Then sometimes they jump ships to their buddy's SaaS company and get a nice fat salary as a reward for having helped to create the parasitic dependency.
The OccupySaaS people are delusional thinking that the system works well enough and is honest enough that a solution exists within the confines of that system. Same delusion the Occupy Wall Street folks had. Didn't work out for David Graeber, did it? The tech sector is fully and thoroughly owned. We're not heading towards feudalism. It's already tech feudalism. The tech landscape has been fully monopolized. You can't do any business in tech without the approval of a tech overlord.
There is 'how the situation looks' and then there is reality which is 100 times worse.