But I already know from real life that if there's maintanence in blocks 5 to 15, that's eleven blocks under maintanence. With half-open ranges, it once again introduces confusion and makes things unintuitive.

We can each find countless examples where each style comes out better, for eg `1:N` most often expresses the intent better than `range(N+1)`. I find people who prefer half-open ranges to be weird and incomprehensible, you probably find my preferences the same, I just don't like the categorical statement often made in this regard that one is inherently and universally superior to the other.