Wish people wouldn't do this, though I do understand the motivation. IMO it ends up punishing other Internet users (who are the ones getting value from years-old comment threads) vastly more than it punishes the owners and employees of Reddit, Inc. (who get most of their value from people participating in active discussions and seeing ads along the way).

The end result is that you search for "how to fix a broken curtain rod" on Google and the search results are full of comment threads like

• Anyone know how to fix a broken curtain rod?
  • [deleted]
    • Oh, that's a good idea. How do you unscrew the end if you do it that way?
      • Hello! I have removed my comment from reddit because I don't like the way they're running their company. You can find me on Lemmy.
        • Thanks! That worked.

Reddit still gets the revenue from the ad at the top of the page, so the only person you've successfully stiffed is the person who was looking for an answer.

That's not quite how ads work.

You get fractions of a cent for displaying them, but the majority of the money comes from clicking, and the CTR (click-through-ratio) is how advertisers measure success.

If you've got the full solution on one page, users are more likely to engage in ads. If they follow a link off-site first and continue there, they are unlikely to engage.