Yes, Wikipedia policy pages say to be "bold" with editing, but that only really works for things like fixing typos. If you know that someone might object, you should focus on in-depth discussion and let concerns be addressed that way.
This is volunteer work. They can take it or leave it, but they don't get to complain that people stop being interested in contributing when their Truth By Committee design blows up in their face.
If Goodwill didn't have a dock where I could drop things off and an employee to put it where it needs to be, I wouldn't donate.
You incentivize contribution by lowering the barriers to it.
But I would argue, that it affects quantity and quality in significantly different ways. Meaning that quantity is increased vastly more of the two. Average quality most probably decreases. I.e. given high barrier only the most dedicated are donating, which affects quality positively.
Wikipedia wants to strike some balance between quality and quantity. (At this moment probably push towards quality)
Edit: Where wikipedia clearly fails, is effectively communicating which contributions are desired, ahead of time.
People spending time with good intentions only to finally get rejected, is definitely suboptimal outcome for both sides. (Negative emotions, wasted time, decreased chance of further contributions, bad publicity)
Enough people remain that I doubt they are really hurting for more contributors. But yeah, that's a good part of why more technical or niche topics can be spurious.
But at the same time, less people visit those pages so it hurts the site less.