Why are offline raids so frowned upon?

I'm a fairly new solo, and I am pretty much good at everything in the game besides PVP, PVP is my weak point, I can stand an okay chance in a gunfight and beat counters okay but that's it, i really need to improve my pvp skills.

And because of that, when do I raid, it is 100% of the time an offline raid, simply because it's doable for me, since on an online raid I wouldn't stand a chance and would lose all my boom.

But I recently noticed that when I do offline raids, I often get really angry messages and people all around are really salty about it, and even chat in most servers looks down upon offlines and critcize "offliners"

Why is this? For a new solo like me offlines are the only way to go