> I know I made a stupid mistake by not removing the A record but this could happen to anyone. I would like to see more services only allow for DNS based authentication by adding TXT records.
There is plenty of reasons why one will prefer HTML verification over TXT DNS verification. It's usually faster, and more predictable. Plus DNS are far from being completely secure.
It's also pretty nice if you're a provider hosting a website for the client (e.g. Github Pages, Shopify, etc). Getting them to point an A record to us is hard enough, but at least it's only once. Then you can use HTML verification for setting up LE certificates, Analytics, etc.
There is plenty of reasons why one will prefer HTML verification over TXT DNS verification. It's usually faster, and more predictable. Plus DNS are far from being completely secure.