After reading some more comments, I think I came up with a good analogy to explain this issue, and I wanted to share.

Think of websites like a bar that also has an open mic.

Now, when I go to a bar, I don't want to have to give the bouncers and staff my full name as well as my address. I also wouldn't want them to know that I just came, for example, from a store where I was looking for a vacuum, and then have them warn a vacuum seller about it. A vacuum seller who is then going to sit next to me, while I'm trying to have a drink, and show me a pamphlet regarding the "amazing vacuum" he has for sale.

Ideally, I can also look for a bar that will allow me to come in costumed and not show my face. Or I could ask the bar to delete footage of me at some point, and to not store my ID if I do have to show it to a bouncer at the entrance.

All of that is relatively feasible and within the realm of reason; and all of that are things that privacy advocates might advocate for.

However, what is not feasible, or within the realm of reason, or what privacy advocates tend to advocate for, is the ability for me to willingly go up on stage, say something on the mic which I immediately regret, and then ask everyone present to forget it ever happened and delete any footage they might have of it. No reasonable person would ask for something like that, because it is not a reasonable request.

That is how regular websites work. With federated websites, that becomes enhanced; it's like if the bar you're in has a camera pointed at the microphone, and transmits both video and audio directly into several other bars. So when you go up to that mic, you better make sure you're okay with what you are saying being made public and available to anyone.

If I wanted privacy, I wouldn't be browsing online.

I think an option for full data deletion would be nice for those who want it, otherwise people should also expect others recording their data, which can be published later on.

The privacy stinks you say? Did you know that Likes and Dislikes are public too? That was the most shocking to me. Because it is very much not like Reddit or others.

It's still a fantastic piece of software, with all its flaws, though.

I wasn't planning on doing any banking through Lemmy.

I would encourage you to stay as far away from Raddle as possible. It has an incredibly toxic site-wide culture, and some serious security problems.

As a life long anarchist, I personally find raddle to be a fucking embarrassment. The elitist bullshit is right up there with other political anarchist sites like anarchist news; they're all a fucking shit show and shows why anarchists will never accomplish anything.

I don't think much of Mastodon as it is, so they're free to rag on Lemmy all they want.

This is a big issue because in the EU you have the right to remove your data. It could make Lemmy illegal in the EU

In both services you are basically shouting into a giant megaphone. What’s so private about it? If you don’t want say it in public, don’t say it there.

If you need privacy there are much better tools available such as pgp encrypted email or encrypted Matrix DMs (a nonfederated Matrix sever would be even more secure but rather overkill).

Edit: specified encrypting Matrix DMs. I forgot for a moment that you can send unencrypted DMs over Matrix.

In order for me to be offended, I'd first have to care about that opinion. I don't.

Not sure what the point of "Mastodon's" opinion is? Firstly, Mastodon is pretty big and decentralised, and it has no-one who really speaks on behalf of all its users. Lemmy is not a privacy central network like a direct messenger service. It never claimed to be privacy centric as far as I know. The point is to share posts in communities, and the more that see them, the better.

But it is federated which means posts do get shared to other servers everywhere, and deleting those is not as easy as for a centralised server. Whatever I post on any sharing type service, I consider to be public.

The stuff listed in OP doesn't really seem like much concern. "What you put on the internet is there forever!" is completely true, and things like this should only make it more concrete that you can't rely on your service provider to delete information somebody else already archived.
With that being said, default privacy settings - at least on Kbin - seem pretty bad.

Eww. Well, there is a reason why I try and be extremely careful about what I post nowadays. Don't want to regret dumb shit I said in the future.