On, no question. My Pony 135 had front focus (triplet), as does my Jubilette (pre-War 35mm folder). Both produced good images, as do the hundreds or models of medium format folders with front focus (including my Super Ikonta B 532/16 and Moskva 5). It might well have been the case that it was easier to incorporate the rangefinder on strut folders like the Polaroid 100 family by moving the struts, which moves the entire lens board. Same true for bed folders like the roll-film Polaroids (Pathfinder, 110, etc.), linking to the rear of the rack was much easier than to a rotating lens element way out there.
There is a bit of lost definition, however, between Polaroid 667 or 669 or Fuji FP100c, FP3000b and SX-70 Time-Zero -- which I think is attributable to the longer diffusion path compared to peel-apart film. Like inserting a layer of acetate between negative and positive gives that little edge softness that makes an unsharp mask. FWIW, even being a good lens, I don't find Instax quite as sharp as peel-apart, either (though IMO the color Instax is better than the new Polaroid for sharpness -- Polaroid wins on contrast in the monochrome, though).