Because some people are compelled to respond even if it's not needed. Just like ones that beat a horse over and over.
Maybe some internal need for validation or something, maybe they don't get enough attention at home. Who knows.
But you see this all the time. Guy asks if he should buy car A or car B. Horde jumps in to tell him he's stupid and that needs to buy car C instead when it's not even an option he's considering. They think they know what's best for him more than he does. Because their opinion is the best ever and all other opinions are therefore stupid. That's my guess.
Hey, if you got a stack of 2x4s laying around and this is the only time you'll do something like this, then enjoy measuring and cutting and wedging and banging away. I'll be happy with my tool that I grab, one trip to the garage and I adjust it for any length needed, have it work perfect, put away and it's ready to go for the next few projects coming up. You do you, I do me. Adults understand this, children scream and cuss and call names because you're not doing it their way. Furthermore, I would guess the people that scream the loudest tend to be ones least likely to be involved in efforts to keep our trails open. I doubt you see them at cleanups or government hearings or taking signatures or volunteering or putting in work to for our cause. They tend to be the "internet only" kind of people. Not 100% of course, but more likely than not.
Look at you, for example, and your position on Covid and vax. I never called you a retard or cussed you out, but plenty others did. You tried to weave a fine line in your opinion on that, and I respect others will have an opinion different from me. I talk to you like an adult and exchange ideas. Most others just jump on the dogpile to shit talk you to death. Am I right?