Not trying to be controversial but this sounds like the INCEL version of IT. Why do they want a diploma?, why wont they come back to me?, why would they require me to know, X,Y,Z?... Dunno maybe because their business require those skills?

Don't take things too personally, recruiters are asked for a set of skills, they may contact you if they think you have a shot, but the final decision is not theirs. Take a good look at what kind of position you are aiming for and polish your resume and skills for it.

Also be nice to recruiters, they may consider you for future positions, or their recruiter's friend would add you, or well, just being nice in general is good in a professional setting.