The problem is that people think that decentralization somehow solves the problem.
It doesn't. In most cases, like Reddit or Twitter or Mastodon or whatever the issue isn't that something is centralized but that things actually do cost money to build and run.
Even decentralized architectures like Mastodon need that - and very few people actually want to pay for it. That is why the various efforts to monetize the content, lock down APIs and push in your face ads happen.
The VCs that were paying for Twitter or Reddit aren't willing to do that forever - and neither of the companies are actually making profit or even not making a loss. Whether that is because the business is poorly run or some other problem is secondary but unless they start to make money somehow, they will close down at some point. It is that simple.
The article - like most that spout these 'decentralization solves everything' (same like blockchain/crypto/web3/metaverse/etc.) mantras completely ignore this problem or handwave it away. As if a decentralized system ran on fairy dust and unicorn poop and didn't need to pay for servers, electricity, wages, etc. Sorry, but that's not how the world works, folks.
If you don't want to pay money for a service then that leaves the operator with either ads - or has to pay it out of their own pocket. No "defi" or "fedi" solves that - only makes things maybe more resilient when one operator goes bankrupt or rogue. But the rest still have to pay their expenses somehow.
Also the entire premise is BS - as if online forums were somehow centralized and everyone was prevented from running their own server and community, using their own rules (no "censorship" or "cancel culture"! Yay!) and money (a-ha!). Reddit, Twitter, Facebook etc. aren't the only places where one can have a discussion or post information.