The whole notion of Orthopraxy exists only because modern orthodoxy has chosen to cater to simpletons. This is true for several reasons.
1. Nothing, most especially ideology, can ever be black and white. And yet, frum ideology is most often presented as black and white because it has the convenient benefit of allowing for certainty among simple people, who are the only ones who can accept it.
2. In addition, this leads to a chain reaction – because simple people are the only ones who can accept it, they become the ones who determine its application. This effect led to things like the cherem on “The Making of a Godol”. The “askanim” who agitated for a ban were simpletons. Rabbanim (e.g. R’ Zelig Epstein) who signed on to it conceded that it was appropriate for sophisticated readers but were concerned that simpletons would read it. Thus, the book was banned and people who could have benefited from it lost out in order to protect simpletons.
3. The current definition of Orthoprax is also only possible in a black and white world. It’s conceivable that someone believes in literally no aspect of frum ideology and practices frumkeit despite that. But I suspect that the overwhelming majority of the so-called Orthoprax actually believe in significant portions of frum ideology. It is hard to conceive of or justify someone remaining frum despite believing that it was terrible for his children, or that there is literally no God at all. Rather, people who disbelieve to some random point on the frum ideology continuum are considered Orthoprax despite believing significant portions of the Torah and probably understanding all of it at a deeper level.
4. All frum people could benefit from a bit of Orthopraxy, in the sense that part of Orthodox Jewish belief is that we don’t understand or need to understand everything. In keeping with what I’ve written above, as compared to simple “belief”, it’s probably more meaningful to shake a lulav despite actively not believing than it is to shake a lulav because you think you believe.