Is there a reason to retile or do the floors BEFORE putting in cabinets?

It is much easier to do the floors without having to cut in around cabinets. That is about the only reason to do the floor first. If the cabinets were already installed and you wanted to just redo the floor, would you remove the cabinets? not very likely.

In addition for the reasons listed for putting in the flooring first, removal and installation of the dishwasher must be considered. If you butt new flooring up to the legs of the dishwasher, you may have to cut the legs off the old one to get it out & then hope you can angle the new one in.

Another reason to lay the floor underneath is that if you don't, it changes the height of the countertop & that can be a surprisingly big deal for tall or short people. Also, it looks more finished if the flooring flows under the cabinets, as opposed to just butting.

But yeah, you don't put floating flooring under the cupboards or any appliances.

depends on the type and thickness of flooring - floating floors should not be under the cabinets, thicker floors like ceramic or natural stone that require sturdier subfloors may get built up to high for appliances to fit correctly i.e; dishwasher, refrigerator (if cabinet above) and the stove may not level down even with the counter.

you will be ok with a thinner floor but a thicker option may require you build up all the cabinets

Leveling the flooring with the sub flooring for the tile may be your chance to accommodate your counter top and cabinets better to level fit... I personally would rather have a nice level floor for the cabinets rather than have to trim or shim the cabinets... just my preference

You do not have to do the floor first. Just bump the flooring to the cabinets when you do the floors.

Do the floors first. Not only will it limit the amount of detailed and difficult cutting of floor material against already set cabinets, but having the cabinets placed on top of a uniform floor surface will make it much easier to replace cabinets in the future. Both methods are done, but for different reasons.

If you have floor cabinets in place that you want to keep, then cut and place your floor against the cabinets, using base molding/shoe molding to cover the irregularity of how they meet. Not a big deal.

Ideally, if you're installing new floor cabinets, wait until the floor is installed first. There won't be any irregularity at the floor/cabinet joint then and you'll be in position to remove, re-arrange your cabinets in the future without leaving gaps in your finished flooring.

I'd do floors before the cabinets. The floors need(should go) to go under the cabinets. It is your kitchen, I just hate to see you possibly redo part or all of something, over a few dollars. Best to do it right the first time.