They're completely unreliable without a link to the original tweet. I'm not gonna sift through thousands of tweets to find one from a screenshot just to verify its authentic. I've done that multiple times for shots of stuff that was genuinely interesting or that I just had to verify and its just a huge waste of time.

If I ever designed a twitter clone it would most definitely put some kind of qr code with a link to the post or at least an archived version of it in each post. I'm surprised I haven't seen such a thing already after all these years of screenshotted text being posted as content.