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.
But you were alive for LBJ, JFK, and Nixon.
Hell, pretty sure even Carter is a better case for "left" than this current neoliberal, living off the fumes of the same far-right governance largely in place since 1976.
If Biden updated Humphrey-Hawkins and repealed Taft-Hartley...I mean that might be a case...but being left of conservatives like Obama and Bill...it just doesn't pass the muster.
I'll bite on the latter.
Of course, if I buy into your point of view, it begs the question as to why repeal of Taft-Hartley is not on the front burner of the current Democratic agenda.
The Democratic Party, on the whole, is small-c conservative. Most of the elements of the party you hate most are tolerated by the party apparatus at best and silenced at worst.
And it has to be conservative, because whatever the Republican Party pretends to stand for now
is not conservative; it's reaction, grift, and off-the-wall conspiracy theories.