I don't know, but I feel the frustrasting part with DR is the fact that your first few times fighting a boss with them is a pain since you don't know how or when a boss will cast it.

I mean, for example with Pink Bean, if you fight the statue from the left corner the statue will NEVER DR, but you can't know this unless you ask somebody else. Knowledge burden. Pink Bean DRs themselves are super obvious and doesn't last that long though.

Hilla and Crimson Queel will cover themselfves in a red shield before DRing, but you can't know this the first couple of times you fight then. Chaos Horntail use the same silly animation for damage block when he DRs (though this is easy to avoid, but again, you need to know beforehand). Cygnus lifts her hand and does a teal circle animation before DR, but this is extremely hard to see if you're not used already.

Basically you shouldn't die to DR if you have some reactions and previous knowledge, but the problem is getting the knowledge itself. I feel the problem is not with the DR itself, I feel it is a good mechanic (a way a boss can kill you and something you need to focus about, it adds challenge), but I also feel that in the lower difficulty of bosses the DR shouldn't insta kill you, but should just damage you a bit, so you can practice and learn the DR animation without getting killed in the attempt. By when you fight the harder versions you should have the knowledge and practice already.