Step 1) Offer artificially cheap software to replace employees.
Step 2) Attracted by low prices and productivity, employers adopt software.
Step 3) Software works. Employers lay off employees.
Step 4) SaaS vendor needs to make profit, raises prices significantly.
Step 5) Software is no longer cost-effective to employer, but employer doesn't have employees to fall back on.
"SaaS as outsourcing" is just obviously wrong, as well as "SaaS is rent-seeking" (which seems to entirely misunderstand what "rent-seeking" means).
It's a simple question of make/buy. All your examples are can be either made in house, or outsourced to someone else to make for you.
For example, do we make our own ERP system in house? Or do we use a vendor's (SAP)? Do we pay another company for doing financial transactions, or do we setup our own infrastructure?
Companies that use SaaS products are outsourcing a function... Another example: Do we host our own data center, or do outsource and use a cloud SaaS like AWS?
I find SaaS is just outsourcing, and for whatever reason, management types need to come to understand that outsourcing is not always cheaper. It entirely depends on the circumstances.
Most businesses typically see IT as a cost center because they don't understand what IT is. The ones who outsource don't realize that a highly competent IT staff will both cost a lot of money and appear like they aren't working hard or doing a lot. So in the short term it looks like outsourcing (SaaS) is a way for the company to save costs, than doing things in house.
Frankly, the best analogy to SaaS/outsourcing I can think of is leasing cars...
It's cheaper in the short term to lease a car (i.e. outsource), than to buy a car (i.e. "do in house"). However in the long run it's generally cheaper to own a car than lease one. The exception is, if you have a need for a new car every 2-3 years, then leasing will be cheaper than always buying a new one every 2-3 years...
I think the same analogy applies to Renting vs Buying a house.
Anyhow, I'd argue most businesses would be better off in the long run doing things in house, but that requires paying more for upfront for talent (which makes such a prospect seem more expensive at first glance).