And aside from the ‘bird eat bird’ factor, you have the daily fist-fights at the feeders. Not so much with the little darling 4 — Chickadees,Titmice,Nuthatches and Downies, but the House Finches are squabblers to the nth degree! They not only go after the others, but even amongst themselves, they are always at it!
It's not native to the East, but to the arid regions of the American West. At some point in the 1940s, it's assumed some petshop house finches in Long Island were released into the wild, where they thrived and multipled. From that original population, nearly the entire East has been colonized by the house finch -- for good or for bad.
Since I live in the original range of the house finch (the arid West) I see them all the time too and I definitely appreciate their hardiness. When I perform bird surveys in arid regions, sometimes the only birds I find are house finches (in addition to Gambel's quail, black-throated sparrows, cactus wrens, loggerhead shrikes, verdins, black-tailed gnatcatchers, and a few other hardy locals).
Maybe that's why your eastern house finches are so aggressive -- not being native, they have to be especially aggressive to compete.
Sadly, the population of eastern house finches seems to be declining, due to a terrible eye infection that has infected the population. Ornithologists in the East are keeping a close eye on this. Even though they're not native to your region, they are still a beautiful bird that doesn't seem to be doing any damage to your native bird populations.
It would be a shame to have them extirpated from the East. But at least they're still thriving in their homeland in the West!
Happy birding to ya!