I think that some of the people who say "that's too hard to do" about certain feature suggestions are actually giving some of those features more thought than the people who proposed them in the first place. Some things are impossible (or at the very least impractical from an administrative or gameplay perspective) with the architecture the game uses, and no amount of namecalling will make that fact change. (I tend to give my suggestions a fair bit of consideration on that front, so I think they are all doable).
The arguments you get from some of those people that get called out remind me of the data compression mailing lists and forums I frequented in the past, where you would often get posts with dumb ideas like "why not just compress the compressed data again?", as if you can just keep feeding a giant file through some magic algorithm repeatedly until it's 1 bit long. You can imagine that the responses were suitably "snarky", and the original posters tended to either hurl insults or quietly disappear, shamefaced. Anyone can suggest anything, but it helps to have a bit of knowledge about what is practical from a technical perspective and what isn't.
As for the "this is Elite, not Game A" responses, There's good reason for keeping focus rather than trying to be all things to all people. Perhaps there's room for Elite: Tycoon, Elite: Space Marine, Elite: Survivalist, Elite: Gearhead, and all the other games that people want to play within the bounds of Elite: Dangerous. I think that Frontier would need a cast of thousands to even attempt keep everyone satisfied, and seeing as you can never satisfy gamers, it would be a massive waste of time and money. Far better that the devs concentrate on making the game that they want to play, because it turns out that the game they want to play is also the game that a lot of others want to play too, and most of them probably don't even know this forum exists because they're playing the game.
