I agree with some of this point, as Ubuntu is a fair option to start off with. I used to stay pretty exclusively to GNOME, even sidestepping the more "touch-friendly" style of GNOME 3 by adding extensions to re-add a taskbar and such.
Alternatively, I've poked with KDE (such as through Kubuntu: https://kubuntu.org/ ), which has actually been a lot more performant and slim than GNOME (in stock Ubuntu), and generally what I desire out-of-the-box versus having to pile on more GNOME extensions (which probably drag down performance) just to get the same.
The main downside with Ubuntu is the ways they try to slip in some ways to commercialize their distro sometimes, such as having small text ads when opening a console, or integrating Amazon search (before Microsoft forced Bing into their Start Menu, even) into Unity long ago.
I'd reasonably recommend 'easier' options (such as Ubuntu, Kubuntu, Mint, Debian, etc), versus the trend where I see people that are new to Linux try to take the "hard" option first, because of handling it like a self-image thing, that they're "more advanced/knowledgable than to bother with Ubuntu", but end up failing miserably, and blaming it all on "Linux is total sh't" etc when they fail miserably and can't be bothered to ask for some seasoned advice.
There's probably the bigger issue of culture shock for those crowding to Lemmy as an escape from Reddit, of whether those individuals will choose to adapt to interacting/debating with people dissimilar to them. The problem of Reddit (as one of the reasons I've stopped touching it many years ago now) is some of the insularity of the platform, especially when you have overcontrolling mods in a subreddit that suppresses any dissenting outlook (which then creates a monoculture).
Whereas on the fediverse the rules are very different, since anyone from any platform that also speaks ActivityPub can step in on a conversation. Just a discounted $2 domain from Namecheap and someone's able to set up another instance with little friction. Meanwhile if a community goes whitelist-only, it just erects a wall around the userbase, and typically stops the growth of the instance, with people ditching it because of lack of activity. Even with defederation back to days of OStatus, there'd always be some momentary drama where an admin would block an entire server, often just because of a few users (while users have a Block button they can use; or in the worse case, the admin can block specific users of a remote instance). Nonetheless, that's played out plenty against ShitposterClub for years (of disproportionate server-wide bans), and yet, it's all the ban-happy instances that have disappeared, while ShitposterClub still lives on strong today.
There's going to be instances that'll pop up with abusive admins that'll try to subversively control the policies/moderation of remote instances (e.g. "ban this user of your's, or else we'll defederate you", or more stupidly "don't use this software, because of the developer's political views"); however, admins should never play into that coercion. Even if there's a few friends exclusive to that instance, there's no justification to let a manipulative actor get what they want. Over time, an overcontrolling instance admin will usually try to desperately tighten their grip, and usually any sane people will ditch for better instances--so don't strain too much over unfair acts of defederation in the present.
But ultimately it comes down to whether any "Reddit refugees" will chose to adapt to the broader fediverse, versus trying to recreate the antipatterns of Reddit and ending up with many hundreds of dead Lemmy (or similar) instances instead.
And as a side-point: I wish people could move beyond the useless word "toxic". There's a broad spectrum of vocabulary in English to describe things, while "toxic" is just used as the quick catch-all of "it's just bad, okay". For example, consider how meaningless the above message would be if I substituted the words "overcontrolling", "manipulative", etc with "toxic" instead. Whereas I'm articulating why something is bad, versus just declaring something 'bad'.