A company might switch from Github Enterprise to Gitea Enterprise if they were fed up with GitHub Support (or lack of it) and wanted to be able to run on-prem with k8s.
What you're not understanding is the way DNS works is the closest DNS server to you (usually your ISP unless you've configured it differently) usually caches the results and then serves those results for subsequent requests.
So you are relying upon the server that is caching those results to serve your data. The intent of DNS TXT records was not to provide you with a content distribution network for free.