Tbf a substantial amount of voters did see the comment - at the time of writing, 297 upvotes on the comment vs 483 upvotes on the post, or ~61%. So actually most people do dig through the comments, if the upvote count is something to go by at least.

Anyone who doesn’t read comments is unlikely to read reader added context, so you’re probably not getting a large amount of the remaining 39% of people to get the context just because you add some extra UI feature.

Besides, explaining the context is a much longer affair than a title and just wouldn’t fit. It’s not like I would even say that the title of this post is misleading in the first place, it’s actually pretty to-the-point.

There’s also a chance that people will get the wrong idea about posts without the context - i.e. that posts without reader added context are super truthful somehow. I feel that people should rather accept that all titles of a few sentences are missing context. That is after all the point of a title - to summarize and bring only the most important information, which inevitably leads to a loss of context.

It is implemented. It’s known as “comments”. You are looking at it. There’s no need for any particular UI feature for this stuff.

Unfortunately I don’t think you can just make it illegal. People/companies would still do it, just covertly. Then you end up in a situation where adverts are not marked as such and that’s probably even worse than the current situation, where ads at least identify themselves as ads.