I agree and disagree with different aspects of your statement.
yes, point 1 you make is true in the sense of the holy spirit function of marriage. However, they have not made the sacrament, and a blessing doesn’t change that.
If you are a practicing Catholic in good faith, I would think the sacrament is important for you.
And as sitetest has pointed out, I am assuming too much in thinking that form can be observed properly without supervision.
The personal experience I am familiar with is an "Anglo-Catholic" Protestant marrying a Catholic who became an "Anglo-Catholic" Protestant.
So their wedding ceremony in the Protestant church was very similar.
So I stand corrected.
When I married my wife the Catholic Church wanted $ 5,000 for an annulment from her previous Catholic marriage. This was in 1976. I told the diocese I could not afford it and they said I couldn’t afford to be Catholic and I would be excommunicated if we married. After 38 years I haven’t forgiving them but wife still claims she is Catholic. I do still receive the offering envelopes.