Yes, lag exists for some people. But op is correct in saying in a df group,no one cares about the reason you're dying. If you are doing badly,you're doing badly. Making loud excuses does nothing. If you are a consistent detriment to a df group, the polite thing to do is leave.

I really appreciate that on jp servers, df is for clears, pf is for practice. Much less painful.

Similarly on watching videos, I don't expect anyone to do so for dungeons, they're simple to explain. But ex trials and coil? If you want to go in blind, make a pf. That's what I do and it's much more enjoyable. Doing otherwise is like you're asking for a carry. Doing something first time when everyone else knows what they're doing is not exactly an achievement...