Yes, I use that option too and it is great convenience. However, as you noted STEP is recommended because of greater precision. When I am printing parts that have to fit together, I always use STEP. However, if there is nothing in the model that let’s say 0.02mm variance can’t handle, then the STL export is adequate.
It may help to understand the distinction between the two processes. In the case of the print from app, the app is doing the mesh conversion. In the case of STEP import, the slicer is doing the mesh conversion. Truth be told, I have yet to find a model where I can prove a difference between the two. The only comparison I can give is the number of vertices and size of GCode.
The best example is to test a sphere STEP file that you’ve imported in to the slicer, vs an STL file vs a Sphere primitive and then look at the number of vertices. Higher is better for precision of curves but not always better when dealing with right angles. Most of the time it is better but NOT always.
There was a thread that went on for weeks on this topic and truth be told, there was a lot of BS opinions without any proof. I did my part and tried to post examples of the difference in this link. In that example, I used a simple cylinder. Nevertheless there were some folks who continue to wage the argument that their piece of string was more accurate than everyone else’s piece of string, if I may use that analogy. The bottom line is that math doesn’t give a F*ck what people think.