Those are of course valid points. The counterpart being that a vendor might not have an API because they actively don't want to (Twitter/X for instance...), and when they have one, clients trying to circumvent their system to basically scrape the user UX won't be welcomed either.

So most of the time that path of "build a tool once" will be adversarial towards the service, which will be incentivized to actively kill your ad-hoc integration if they can without too much collateral damage.