Going by my experience, 100% of the people saying "do your own research" are either shills or they are getting into a project without having no idea of how things work. If people can explain easily and if it is a legit opportunity, they wouldn't be saying "do your research", this will just be accumulating as much as they could without making too much of a fuss about it.

Corollary: any coin that is on the up-and-up and you can not easily explain the tokenomics is worthless.

Yes, IMO you should treat a crypto investment as requiring much more DD than a typical investment. You should have a thesis about why a given project is more likely than baseline to succeed, and you should have done enough research in the actual community of users (not just investor shills) to convince yourself that real people are actually using this thing reliably. There is just too much vaporware and outright scams to do otherwise.

Dyor means that they know it's a scam, but they want to avoid responsibility.

It's also a method of making yourself seem authoritative or knowledgeable without having to prove it. It implies that you did your research, but you aren't going to prove it because everybody else needs to do the same for themselves.