Tihs si bcuseae teh huamn mnid deos nto raed ervey lteter yb istlef, btu teh wrod sa a wlohe.
When one is learning to type (i refuse to use the phony verb "keyboarding"), one learns "phrases," which is to say, one learns to type groups of letters, and that without reference to the "sense" or logic of the group. In fact, the old method included speed building drills, in which one would type five letter groups which were intentionally not words or parts of words, in order to build the habit of repeating what one sees without reference to the sense or logic of the groups of letters one was learning to master. I achieved my fastest speed after doing speed building drills (not that i can still do that, but i still type pretty damned fast).
It's silly, though, to claim that spelling doesn't matter. It becomes even more crucial when one its attempting to understand someone who doesn't express ideas well. They're, their and there are words for which the spelling is crucial to understanding the meaning. One might allege that the strict insistence upon spelling might be relaxed, and that's not unreasonable--Noah Webster demonstrated that. But to abandon spelling standards altogether would be foolish.