My guess is that this is that this is for use-cases where that's not a big concern, or at least where that concern is outweighed by the easy of use.

Some examples off the top of my head:

- I'm selling something to exactly one person - I met someone on discord and I'll sell them a writeup on how to do X in language Y for $5, or I'm selling an art commission or something. I use this service to send them a link.

- I'm selling a somewhat niche infoproduct - the "Expert's guide to using jq to parse stripe data" or something. I expect most people to find it via my blog or newsletter where I talk about jq a lot. I don't think many people will pirate it and I use this paid link to distribute it.

- I'm selling something time-bound, like "Joe's guide to the 2022 world cup tournament for programmers," and I expect that I'll make whatever money I'm going to make on this guide pretty quickly before people get around to sharing the link for free.

- I'm selling something that's paid now, but that I plan to make free next week. "Click this link to buy early access to my yadayadayada!"

If you want to actively prevent sharing of the post-paywall content, Gumroad and plenty of other options already exist for that use-case.