About 25% of my RF photos are < .7m. From 50/1.4 lux (e46), 75/1.4 lux, 35/2 cron, and even M-Hexanon 28/2.8.
Inconvenient, but it shouldn't be much of a surprise since there are few rangefinder-couple lenses that can get much closer than 0.9m or so. It's not that the manufacturers couldn't make the lenses focus closer -- it's just that the optical and mechanical limitations of a rangefinder camera make it difficult to take advantage of closer focus.
To name two:
-- The lens couples to the rangefinder via a pivoted arm in the camera that swings back and forth, and there are both mechanical and geometric limits on how far this arm can pivot.
-- The rangefinder and viewfinder windows have to converge their viewing angles on the subject as you focus closer; eventually it's possible to get so close that the two windows are seeing the subject from noticeably different viewpoints, which makes it hard to line up the images. I used to have some prismatic "Auto-Up" close-up attachments for my Canon VI-T, and at the closest distances the finder view got noticeably "cross-eyed"!
It's possible to design specific lenses -- Leica makes one -- that will focus closer, using viewfinder and extension attachments to get around the above problems -- but they're still a bit cumbersome and not nearly as flexible as what you can do with a camera that permits through-lens focusing.