Title talks about “the internet”, your text talks about “social media” - and threads so seemingly a subset of social media.

The internet doesn’t make it hard. It’s incredibly easy. Sending emails is easy. Hosting a website is easy. Posting to platforms is easy.

Platforms and communities restrict - through their own rules - what they deem acceptable within their own scope. That’s more about defining scope than “making it hard”.

Reasonable self promotion is often accepted on reddit and lemmy. Blatant advertising is not. Be part of the community, or run an ad for an ad. Be a good participant rather than a spammer.