I know many conservative Catholics who exclusively go to the OF.
So do I. And I never said its impossible. What I did say is that many people who are conservative and were in OF parishes, saw themselves as a small minority in a sea of luke warmness and modernism. Many of them tried to do things to fix the situation- talk to the Priest, write to the Bishop, work on the Parish council, become a lector/cantor/choir member/EMHC, etc.
Then rightly or wrongly, they decided they would rather go somewhere they didn’t have to fight within their church for orthodoxy and reverance. In many cases, this decision came around the people became parents- because while they were morally prepared for the struggle within the OF community, they wanted to raise their children in someplace where the faith was clear.
This is what happened in my family. It’s also what happened to many other families I know. In fact, I know some folks who have told me they prefer the OF…but they go to the Latin Mass because they can’t find a reverant OF Mass- this in a large northern city where there are many, many churches within a short distance.
Are there coservative, traditional Catholics in OF parishes? Absolutely. I know many of them. Perhaps they’ll come to the EF as some point. Perhaps not. The fact remains, that MANY of them have come. And when a lot of folks like that are concentrated in a Latin Mass Community instead of scattered about various OF parishes, a few things happen:
-they are greatly encouraged by knowing people like them

-they can speak with a louder voice.
It does set up an interesting dynamic, where if the Church gave us “what we want” or at least what many want- the EF everywhere, say one EF Mass at each Latin Rite Church each Sunday- it would destroy what has been built. That tightly knit community that can fill a large church with EF enthusiasts because it draws on a large area would be gone. THEY would be scattered among various parishes all over the place. That’s a scary idea for a lot of people. I have faith that the same things about the EF that have shown the fruits of the Holy Ghost in the Latin Mass Community- lots of kids and many men following a vocation to the priesthood being two big ones- would manifest themselves all over the place. It would take some time, but expanding the celebration of the EF would draw more people in and grow the Church. In large part this would be because it would enhance the cooperation between “traditionals” and “traditionals”.
Pax and God Bless.