I'll back up what others are saying. Hormones need to work in balance and when you throw one off, it can ruin everything and that is why it takes so long to get TRT correct. You need to make sure you are aware of all your hormone numbers ie, test, free test, cortisol, dhea, pregnenolone, e2, and shbg.
As far as the question regarding estrogen- no, it is not broscience, it just happens that people are finally becoming more aware that test is not everything. You need to keep your estrogen in ratio with your test levels. On TRT, it is difficult because we are responsible to doing what nature does with guys not on it. High estrogen is bad in any case, but low estrogen is too.
I personally like to keep my total test in the 700-800 (250-1320 scale) range, free test in the 30ish range (5-40 scale), and e2 in the 15-25 range (3-70 scale).