Text and database entries are, indeed, Vastly lighter on resources (compute and bandwidth). Bandwidth cost for text is practically free. Managing voting is surely not easy though; every single vote is an additional database entry which means that they cost money to store. Then the vote sorting algorithm has to run pretty frequently. Comments themselves are probably nothing compared to the votes.
But managing voting and sorting is a one-time-cost. Reddit doesn't let you vote on old things which means that they can completely discard the votes and keep the totals and never resort ever again. They have no real ongoing costs there.
You've never run a website or a server have you. Servers today cost almost nothing. You can get a high quality virtual private server for $4/month or run it in a closet at your house for free on an old laptop. That can handle thousands of simultaneous website visitors for everything except a huge video streaming service. A recipe site would cost absolutely nothing out of pocket. You are seriously overestimating the costs of these things because the big tech companies propagandize the public. But you may notice that none of the big publicly traded tech companies actually ever say how much they spend on servers specifically - because they don't want the public to know how low the number is. Except for Wikipedia that is: out of >$100M in annual spending, <2% gets spent on hosting costs.
It was easy enough in the late 90s for millions of teenagers to figure it out and make their own web pages and easy enough for millions more to get their MySpace page to sparkle. You are over estimating how hard this stuff is. It's not hard as evidenced by how many people in the last generation successfully did it.
The overall problem with your post is how often you refer to things online as "content". It never used to be "content". They just shared their writing, their opinion, their art. There is still a desire to do that! But years ago readers found things via a "web" which was free (clicking links is free) but today they find things via private algorithms which inject ads. That's what went wrong.