I'm in the business. Depending on the size of the kitchen and the type of flooring, running it under the cabinets can be fairly expensive for something that doesn't show. On a fair size kitchen you can easily spend an additional $1000 running flooring under the cabinets. In addition, all it takes is for someone to drop a tool during installation to ruin your day and take any profit. With 3/4" hardwood flooring, it's simple to raise the cabinets just by laying down some rips of 5/8" ply. The flooring is installed under the range, ref and dishwasher so that's not an issue. Another concern is that floors often get replaced before the cabinets. Fairly simple when they butt against the toe kick, not so easy trying to cut flush with the toe kick in the future. Experienced flooring installers don't have any problem fitting clean and tight to trim and cabinets. Today, many flooring guys don't have those skills. They would rather lay the floor and then the baseboard and cabinets. Usually the baseboard shrinks, leaving an unsightly gap. It's also a lot easier shimming cabs on the subfloor, if needed, than having to scribe the toe kick to the finished floor.
We always do flooring last, after everyone else is gone, cabinets are installed, light fixtures are up and finish plumbing completed. It's too easy for a worker to make a mistake and damage the floor, carpet, tile or other material. Damage can be very expensive to fix and it can hold up the final payment. It's not worth taking that chance. If it's your own place, do as you dare. You can look like an idiot if the battery drill falls off the step ladder, somebody has a stone stuck in their boot or any of a hundred other possibilities. Doesn't matter how much padding you put down. Been there, ain't going back.