Not in my experience it isn’t (modelling in tris that is). There’s loads of benefits from using polygons (mostly in terms of modelling tools, but also in terms of a cleaner display). The only benefit of triangles is that as that’s what the end result will be you get a more accurate count. Any decent exporter will convert a polygon model to tris on export, or if it doesn’t then all you have to do is convert the model to an editable mesh before export, or put a turn to mesh modifier on the stack or similar. There’s no need to make all the edges visible for it to export.
You can display the triangle edges in mesh or polygon mode using the object properties or display option- ‘display all edges’. I’ve got it bound to a key as I toggle it on and off all the time.
One slight benefit of meshes is that turning edges is a little quicker than editing the triangulation in poly mode, but the results are the same.
I would never, ever make all the edges visible, or triangulate a whole model as that stops things like edge loops and rings working (they rely on quad faces). But if you must, then the easiest way to triangulate a model in poly mode is to select all the verts and connect them.