Pressing him on an issue and trying to get him to answer it, or fact-checking him in real time, isn't an attack. That we've sunk so low that what used to be bog-standard debate practice is now considered an "attack" is depressing.
And maybe that didn't happen with Biden anywhere near as much as with Trump because he could answer questions? Because he wasn't making shit up? Y'all expect them to be treated the same as if they act the same. Biden didn't spend yesterday morning trash talking ABC and the moderator before showing up to his debate. Trump did.