We are social animals. Literally just existing is stressful at the moment for most of us, because there's a constant urge that is not being satisfied.
Not only for socialisation but simply the low-level stress of constantly having to 'check yourself' when you realise literally everything you'd normally be doing is either disabled or handicapped in some way.
To me, lockdowns feel like some sort of irrational loss aversion strategy. If you gave me the option in, say, 2017, of halving my mortality rate for a year, but the cost was that I had to endure relatively strong anxiety for that year, there's no way I'd take that bet regardless of my age.
Mucking around with your mental health is not wise. Add on top of that all of the economic effects, the political effects of dividing populations, domestic abuse, "non-essential" healthcare like dentistry, and so on and so forth, and honestly I reckon it's been a net negative.