What is the usage of CYK algorithm in the real world considering we have algorithms with a much better Time complexity? So considering CYK is O(n^3) and since we can just use LR(k) algorithms for DCFG's which they can check if a string is in the language in O(n) then whats the usage of CYK?

is it being used anywhere?

If I'm not mistaken(correct me If I'm wrong) the benefit of CYK is that since we can convert any CFG to CNF form therefore i guess we can apply this to non deterministic CFG's and also Inherently ambiguous grammars which are CFG 

but are these really benefits? i mean whats the usage of using membership algorithm for Inherently ambiguous CFG's or non deterministic CFG's? where would we use a Inherently ambiguous CFG or non deterministic CFG ?!

Isn't the main usage of membership for compilers? which they already use LR algorithms?
Here is one benefit:

Some grammars aren't LR(k).  Then it's useful to have CYK or some other form of GLR parsing.  GLR parsing is used in some compilers, where the most natural way to express the grammar leads to a grammar that isn't LR(k), or where ambiguities are resolved in a later pass (not part of the parser).