The real reason is that Donald Trump( and his cult fan base and administration) has exhausted the country for a good while from politics. So it seems like it hard to turn up the ante after 4 years of Trump. It also helps that Biden is an older man who is more moderate than most of presidential candidates and a good chunk of congressional democrats. Lastly it does seem like the conservatism we know of is losing a bit of its flavour and steam so it has reinvent them self into something else especially the nationalist types(See Bolsonaro, Modi, Netanyahu as examples who are losing some goodwill in their own countries). Maybe try to be more like Boris Johnson but we'll see.
This is a interesting take from the article
And there’s another problem, Goldberg told me: “Most of the good ammo against Biden—which I’ve deployed in the past—isn’t as effective after four years of Trump. He says crazy things! He doesn’t know what he’s talking about! He has a ridiculous ego and lies about his brilliance and expertise! All of this is true. But all of that has been normalized by Trump.” To a conservative movement that has been “mainlining crazy for five years,” it’s hard to get excited about measured criticism of Biden and his policies
The highlighted sentence is simply not true.
Whatever Biden may believe as a person, he's governing the farthest left Administration in my lifetime.
No American administration in history has even come remotely close to being 'far left'
