No, "new" would not be fine. Being forced to make an account to see certain content is not fine. Being shown one comment depth at a time is not fine. Burning vast amounts of RAM is not fine. It's a trash fire. Intentionally so, one suspects, to shepherd people towards the app. The whole reason they keep "old" around at all is because they know that "new" sucks.
IIRC I think a Reddit dev commented here on HN saying that that was the case. Can't find it again unfortunately, but it was the most popular top level comment on a thread about Reddit
> I mean if they got rid of the popups and nagging to install the mobile app, new would be fine
Sure, but they haven't, and they won't, so it's not. They constantly run A/B tests that include some pretty aggressive variants, too. Many of those completely lock out reading posts until you're signed up or using the app.
In old Reddit you open the link, see the content, and close the tab. New Reddit is heavier, slower, more aggressive towards requiring an account, specially on mobile.