Because those planes have the payload capacity to carry more than what their inner stations allow, whereas Anka-3 doesn't. Carrying 4 small bombs instead of 2 big ones isn't exactly a "beast" mode either.
Not to mention, comparing Anka-3 to F-35 is comparing apples to oranges both in terms of its class and shape. If anything, the comparison should be B-2 or other deep strike crafts, which do not feature outer pylons. Flying wing design is most useful when it is used for deep strike, not a2a engagements, even though I know TAI keeps saying it can also do that.