It matters.

Democrats accomplished a lot in 2021-2022 despite having razor thin, bare majorities. Not as much as in 2009-2010 when we had huge majorities, but a lot closer than you'd expect from that. The reason is because the party became far more ideologically coherent in the time since. If we had a 50 seat senate in 2009 we'd have struggled to even rename post offices.

Likewise, the dem house has been far more unified in opposing Trump than past house caucuses have been. This forces republicans to actually have their shit together before bringing any legislation to the floor. That ultimately won't stop them, but it will slow them down and result in them needing to leave things on the cutting room floor before the next congress is sworn in.

Better dems means we can do more with less and that republicans can do less.