Stuck Valve-Yukky Water

The house I just moved into had low pressure on the cold side of the kitchen faucet. Turned out the cold water shut-off valve had seized up years ago in a mostly-off position. I broke it free, and you wouldn't believe all the crap that came out. The first few minutes, the water was completely rust-colored, then huge flakes of rust came out for ten minutes, and even after several days and a hundred gallons or more, the cold water still comes out with debris mixed in. I could filter it, but I don't want to ruin expensive filters.

Does low pressure cause pipes to corrode faster, or would all that corrosion have passed through a little at a time if the pressure had been higher for all those years?

When water goes through a restriction to its flow, the velocity of the flow has to increase. If the water is hard, scale can form at and in the restricted area. That then traps sediment that will build up as much as it can. The pipe at and before that valve, and the valve itself, may be full of scale and such.