I don't feel that is an excuse really
For example, Jodie Foster and Hilary Swank won both their oscars in between a few years of each other. I think there was two years between The Accused and SIlence.
Whether they have won recently or not, it isn't an excuse for someone to be nominated. It took them 30 years to give Meryl another oscar because nearly every damn film she gives the performance of her life so they were spoilt for choice.
Jodie's wins were a while ago though, and there were 5 years between Hilary's wins, that's true, but she hasn't had a look-in since, and Marion has only just passed 5 years since her win and is regularly at least close to a nomination. She'll get her 2nd nomination/win I'm sure.
I'm not saying that a recent win is an excuse for someone not to be nominated, I'm saying that recently it seems the Academy does think in that vein, at least some of the time. There's a difference.