A man should only propose marriage if he is financially independent/self-sufficient to the point of supporting >2 (!) people.
In doing so, he is asking her to risk complete economic dependency on him (she may have an income, but it’s not guaranteed/required). She may, during the engagement period, leave her other source(s) of income - trusting that he will indeed support her.
The engagement ring is (in my view) literally wearable wealth: enough easy-to-liquidate value to, under whatever circumstance, provide for her basic needs for about 3 months (enough time for her to acquire other income streams). Should he bail out of the engagement, she may need resources to resumer her own independence. If he can’t provide her 3 months’ wealth up front, he’s not ready to support her. That it’s pretty is just a bonus.
Having her obtain him a “man-gagement ring” dilutes this: he should not be in a position to need such portable liquid wealth (and should provide his own reserve out of prudence), the cost diminishes her financial reserves, and ignores the biological realities that _she_ is the one prone to being financially out of commission (transitioning to dependency upon his income/wealth; possible pregnancy).
Insofar as feminists may object: he’s not the one likely to get pregnant, she is - and the greatest contributor to poverty is trying to be a single mother. Having that “3 months wealth” on her finger can at least get her through the toughest financial period she could face. Yes, procreation is the primary point of marriage (not “feelings” - those exist to induce reproduction).
She doesn’t have to be financially beholden to him, but realities of human sexuality mean she’s far more likely to be than the reverse. THAT is why he gives her a pretty - and expensive - ring to clinch engagement.
That was a tour-de-force of white night thinking