Like you can say people spend too much time on TikTok, but if it wasn't TikTok, it'd be Twitch, or YouTube, or Netflix, or Instagram, or Reddit, etc.
Right, because they're pretty much the same category of service, addressing the same niche.
To both yours and GP's points: it is true that "what is addictive to someone is harmless for someone other". This is true for alcohol, tobacco and gambling too. Yet we know that unchecked, these three cause tremendous social problems - and so we've adjusted both regulations and culture to find a balance between freedom and protecting the vulnerable.
In particular with social media, I don't like the framing of it as "what is addictive to someone is harmless for someone other". The addictive-ness is baked into the product whether or not an addiction is manifest in any individual user. Viewing the addictive-ness of say, Facebook, as a problem only "for some people" rather than as a property of Facebook, shifts blame away from the engineers and execs who purposefully make their product addictive, onto users who find themselves (somewhat innocently) addicted to an the addictive thing.
Don't want to be pedantic but I think it's an important point.
When you have a market niche - then sooner or later it will be filled. It does not make much sense to blame "concrete companies" - because once you close them they will be replaced by others. You need to make laws that would close the niche of providing the 'particular types of services that are problematic' entirely. And making those laws is difficult - because forbidding something always limits the freedom. There are lots of people here who believe that drugs should be legal.
And it is internet and smartphones that created these market niches putting us into that awkward position. It is also practical to focus talk on them - because there are concrete advice on how to configure your (or your children) smartphone (or internet connection) to make it less addictive. It is something that can be done without any collective action problems.