Competitive matches already don't pick up the newest patch immediately so that new bugs that haven't had time to be fixed don't interfere with the matches, and also so that the pros will have already had 1-2+ weeks of practice on the patch to adjust to changes. The entirety of Worlds is on 5.18, for example.
What the OP is saying, is that outside of the competition they can play on the old patch that they'll be competing on (they may be on 5.18 at Worlds, but when they go home they only have access to 5.20). He thinks they should have access to the prior patch to practice more.
So anyway, professional matches are already viewed on a different patch than is live until it catches up (and until the next patch goes live).