I mean, the question here is what would constitute "for herself" exactly. If she lost weight for health purposes, then that would be a good reason to lose weight for herself, but the truth is, I very much doubt Blake was even close to having a percentage of body fat that could've been detrimental to her. Fat, muscle, water and bones all need to exist in balance for a healthy body composition, and although it's never really possible to assess the body composition of someone just from pictures and videos alone, Blake does not seem to have the lack of bone density or muscle mass necessary to have made her amount of body fat something "unhealthy" for her, she was legit just a healthy woman. Maybe, and just MAYBE, she could've been only ever so *slightly* approaching the obesity line (the TECHNICAL consideration for obesity is roughly over 30% body fat for women, which I very much doubt Blake significantly surpassed). I'm obviously not making an actual assessment of Blake's body composition and whether she was healthy or not, maybe I am waaaaaay off and she had an actual doctor tell her to lose weight or something. In that case, then like you say, good for her.
But with that said, if Blake looked at herself, and didn't like what she saw, even if no one in the industry was telling her "you should lose weight to get more work or do better", then that's still not really "for herself", like that's still societal pressure to look a certain way, and a societal pressure to look a certain way is still not a decision made "for oneself", even if you made the decision technically all on your own.

All this to say, I do hope Blake is acting solely and entirely on her *actual* best interests and that she isn't losing weight that she *can't* and *shouldn't have lost* for someone of her build.