The flooring beneath the legs of kitchen cabinets that are in front of the toe kick board typically does not provide significant support for the cabinets. The main support for kitchen cabinets comes from the wall, as they are typically secured to the wall studs. The legs or adjustable feet of the cabinets are primarily used to level and stabilize the cabinets on the floor.
Therefore, you can usually replace the flooring beneath the legs of kitchen cabinets without worrying about support problems, as long as you take care not to disturb or damage the cabinets during the flooring replacement process. It's important to ensure that the cabinets remain properly secured to the wall and that their stability is not compromised. If you have any concerns or uncertainties, it's advisable to consult with a professional contractor or installer to assess the specific situation and provide appropriate guidance.