I think you can also see something fundamentally positive in the critical attitude of many Lemmy users: namely the fact that criticism of undesirable developments in politics, society, the economy and so on is practiced here at all. In my opinion, this is important and should not be taken for granted. If only because it is impossible for so many people in numerous countries around the world to express their opinions freely and criticize their governments or powerful people in their society.
In any case, I think that a certain fundamental skepticism towards the existing power structures in politics, media and business is something of a unifying element that motivates many people to participate in Fediverse, after all, this platform is an alternative to the centrally managed social media providers and their functional logics.
Nevertheless, I think your post is important because it shows that all the negativity that goes hand in hand with a critical examination of the numerous problems in the real world is extremely off-putting for many users. This is of course problematic both for the mass appeal of the Fediverse and to a certain degree probably also for the mental health of the user base.
Unfortunately, I don’t have an answer as to how to deal with this in a meaningful way. However, I try to stay positive and hope for the best.