Earlier quoted context omitted.
Some subreddits are super hard yes (like /r/roastmystartup), but that doesn't mean that all of them are! In fact, I've been roasted in a few subs and get some really good feedback from others. If you want to validate an idea, just get as much feedback as possible. The negative ones are the better most of the time. You learn a lot from them!
This was not /r/roastme/ or /r/roastmystartup/ it was a perfectly normal (for Reddit standards) hobby/niche subreddit and I didn't ask to be roasted, I was offering help as in "hey I built a thing to help you, what do you think? And then I was eviscerated.
That's really not the majority. What i understood afterwards was: the guys there weren't my target, my product didn't help them at all. They felt like I'm promoting out of the blue, and i got my ass kicked.
I just moved on and found a most targeted subs