I can get past individual Protestants who were bad actors, the thing that is hard to get past is going to a Protestant Church just to greet your friends, with no care for the worship service.
If you go to a Catholic mass, I would doubt very highly someone is going to try to make you feel bad, incomplete or flawed. They are not going to point out your personal sins or probably even your particular denominations’s errors. I could see Catholics teaching the Catholic faith, which by it’s very nature condemns separation from the Church, just as Protestants condemn people leaving their fold.
If anything is incomplete, it is the sacraments of Protestant churches, there have always been seven sacraments, yet the reformers threw away sacraments over time or all at once. Most Protestants have an incomplete set of sacraments, only 1 or 2, usually at least baptism.
The Sacraments help us do God’s will. Sacraments are what God does for us, they are helpers on the way.