It sounds very funny for you to think that Real Madrid allowed Barcelona be at point where they are now. That's not, you just give excuse. Real Madrid can't allow or give Barcelona the chance to win because they are all fighting to win the league, if Barcelona ate doing well and ahead it doesn't mean because Real Madrid allow them.
Not a single team allows its opponent to perform well and get a championship trophy at the end of the season. If there was, then it would be very strange for the team. Because it is clear as you said that all teams are fighting for the championship and the league trophy they want at the end of the season. So there is no reason whatsoever for a team like Real Madrid to give permission for a team like Barcelona to be in the position it is in now.
It made me laugh, how could anyone think a club would let another club win, moreover it was their eternal rival club. All clubs will compete in a race to stop their opponents from becoming champions, even if it is a weak club. In the minds of all clubs, their target is to become champions, but this comes back to their situation which makes them only target the top 4, top 5, top 10 or even staying in this competition. But that doesn't mean they don't want to win, in other words they measure their ability to be able to sit in which position.