Why don't all phono preamps include a rumble filter?

I had 3 different  VPI turntables, a HW19 MK4, Scout And Prime.  All 3 of them neccistated a KAB Rumble filter.  Like yourself, I couldn’t move the turntable from its position. I tried everything I could think of, 4 different types of platforms, different kind of footers, etc. Nothing changed the rumble.  Recently I switched to  Technics SL1200G turntable, using the same cartridge and lo and behold, no more rumble.  It must be something in the design of the VPI tables that helps amplify the rumble.  At any rate, I am very pleased now.  

I was Just thinking, as you and I are kind of in the same situation, one of being shoe horned into a given set up in a less than favorable room, you might want to try a Symposium ISO platform between your table and shelf in your wall rack. 

U@stereo5 
interesting, that you've owned 3 different VPI tt's, and you had the same problem with rumble, until you inserted a different TT.  Hummm?  Makes me think.

@tooblue 
i have a 3" maple platform, mounted on top of multiple 2" square rubber/cork/rubber isolators, on top of my wall mount.  However, I agree with you that, "with a table such as yours there should be no need".  Unfortunately, the need is present.

To restate my original question, why wouldn't the manufacturer of a high end phono preamp include an option to include a rumble filter.  If it's not needed, the user could disengage the filter, if it's needed (and obviously there are many others who could use this option) the user could choose to engage it.

I believe that in the truest sense they want there product to shine in its best light, kind of forcing us into addressing any issues and not making any compromises. Just sayin.

There is no reason to think about changing tables, I too have had three VPI tables never having a rumble issue with any of them, all supported by a lead balloon turntable stand so I started out with a good set up from the ongo. Symposium makes an insert to replace the rubber grommets that vpI uses in their feet that really work wonders for around $200.00. You should be able to get that rumble thing under control with very little effort.