Don't see it that way. If I set up a process once, using software that's been tested and been around for a while, it's extremely convenient. And free. And there's no risk of deplatforming.
Ask any founder here: people don't generally randomly throw money without getting value; ergo these multibillion dollar services you're pretending are entirely replaceable with free tools offer some additional value .
What if someone applied your own logic to buying your product (why pay when I can get the exact same thing from free tools)? It'd be annoying and generally wrong, wouldn't it?
That is completely different from what you are saying now...
Also, "that value can be found elsewhere" is a devious little shift in the meaning of the word "value" in "value prop". Nice try but no, that isn't the same thing.