Because on this issue, both sides literally are the same. If anything, you're engaging in the fallacy that because they differ in some ways, that means they differ in all ways.
I don't get it. Two people stand in the same spot. But they took different routes to get there and they have different destinations. They even stand differently. They don't talk the same, they don't dress the same, and in fact one of them looks like they will rob you.
But I guess if the entire point was "Look. Two people stood in the same spot." then... yes. It's not a useful observation but it's technically correct.
Trump was rightfully criticized for his immigration policy. Biden carrying out the same policy should be criticized as well. It's not as innocuous as simply standing in a spot.
Criticism is as valuable as the metrics and thoughtfulness that went into it. "Both sides" is less than low hanging fruit, it's rotting, inebriating trash fruit. It's like an intrusive thought that people need to learn is a simian brain glitch.
If both political parties share the same terrible immigration policy, do you think it cancels out and isn't worth discussing? This sort of thoughtlessness would explain democrats being so dismissive about genocide just because both political parties support it. What's really "simian brained" is being fine with terrible policy because your political sports team is carrying it out.
"Both sides" is not discussion or criticism, it's a fallacy.
I'm excising the fallacy.
What team do you think I'm on exactly? I don't think people should shit on Trump by calling him fat. I'm conservative. I don't think Democrats are as bad as Republicans. I'm liberal. I think geopolitics is a hard game to play. I'm Kissinger.
Or maybe I'm just someone who doesn't do tribalism to the same degree? Maybe I'm a one man sports team?
It's a discussion and criticism of the policies of the current president and the two-party system. What's your point? That you don't like someone pointing out that republicans and democrats are the same on certain issues?