My X2d wants to create a purge tower, Why? I thought with two nozzles we were supposed to use less filament, ? If I select no purge tower, I get a pop up message warning me that the model would not print correctly !
Prime Tower. For Priming.
Your building nozzle pressure to ensure the best print quality, not purging filament.
Yeah, many of us like you do just believed on the ads and did not educated ourselves too much on time ( before get x2d 
). So now when you switch from single nozzle 1x material/filament for both model and support you get to two nozzles where it is recommended for every FDM printer and brand to have prime tower ( you can disable it ). And basically for small details you get like 30-50-100% more time for printing, and you waste muuuuch more filament. Also it takes space from the plate. If you print big enough jobs it become smaller part of the total print.
Partially good news is that in the latest releases of bambu studio you have some settings which could make the tower smaller.
Now if you need fast prints there is no replacement for the single nozzle/color/filament.
If you really need separate material for support then you have two options, use it with prime tower and waste more time and material - for the ultimate quality. Or just disable the tower and call it a day. And hope for no issue, or tune here and there to mask the issue.