Not true. Were it so, it would not make sense to talk about transfers between spouses, and the tax treatment of same.
Also, at least in Scots law (which I think differs from English law on this point), there is no automatic amalgamation of pre-marital assets into the pot. Any transfers have to be explicit. By default, each spouse continues to own 100% of what they owned before, and would be entitled to retain that when the marriage ends.
Speak for yourself. I married a nice girl, I did, and did not get shafted when we divorced.