My contractor did the entire tile floor before placing the cabinets on top. I do not have a floating vanity either.

I just finished a remodel and tile floors were installed before the cabinets and went under the cabinets. Mine were not floating cabinets.

The reason the "flooring first" practice has become common is due to manufactured cabinets being exactly net. Custom cabinets are usually plus floor, installed before.

In new construction, flooring is usually installed last, after cabinets, counters, tile, etc. Cabinets are measure prior to drywall, plumbing, electrical, etc. with adjustments for thicknesses. Apply toe kick finishes after flooring and possibly avoid added trim.

Watch for appliance clearances. Most KDs are aware and understand the nuances, but If your just purchasing boxes at the store, even if there is a nice desk and design software, you are the defacto KD and its your responsibility.

FWIW, my cabinets were custom and all my flooring was installed prior to installation of cabinets in kitchen and bathrooms.

All of my flooring is level so the tile tile floors in the bathroom are the same level as the wood floors.

I always run the flooring under the cabinets. In most houses the floors (should) last a lot longer than the cabinetry, you don't want to be left with a gap to fill when replacing the vanity. Makes life easier for installation as well.