Don't federated instances just exacerbate already existing problems with places like Reddit, Tumblr, and Twitter? Specifically admin/mod abuse, excessive reposting/cross-posting, server lag/issues?

So considering there’s a substantial push to get away from places like Reddit and Twitter, as an outsider I’m wondering how the fediverse is going to actually provide solutions to some already bad problems within higher resource platforms:

ADMIN/MOD ABUSE: Redditors are no strangers to mods/admins nuking comments, astroturfing, signal boosting/silencing, and so on. Doesn’t that problem just become worse in a federated system? As an example, a subreddit mod may ban users for whatever reason, but a lemmy instance admin could drag all their communities into their own drama if they choose to defederate, no? Losing access to entire instances instead of just one community/subreddit based on a power-tripping admin seems a big flaw. Am I missing something?

REPOSTING/X-POSTING: Reddit was already just the same tweets posted to like forty different subreddits, recycled weekly. On lemmy, there are now a handful of instances that contain virtually the same communities too. The lemmy.world/c/memes and lemm.ee/c/memes communities will post virtually the same content. And that’s just one. Aren’t feeds going to be overrun by duplicate posts in /All?

PRIVACY: I have no clue about this… are there extra security or privacy issues with something like lemmy?

SERVER ISSUES: This kinda goes without saying, but a small instance will already struggle to host even their own local users as traffic increases. Communicating across more and more instances is going to be extremely taxing. Access issues/desyncs seem like they’ll be inevitable. Doesn’t a federated system have more trouble scaling up than a centralized one because of this? How could small independently run servers keep up with exponential processing costs? Won’t this just squeeze out smaller instances? Add this to issues when instances choose to defederate, and you have two competing incentives: spreading out users to keep server stress low, and centralizing users to keep local engagement high. Isn’t this kind of a big hurdle?

Sorry for the wall of text- excited about lemmy in general but really have no idea about whether these are issues.