They used every trick out there at some point. They even invented a new technique for 2 shots in Bag End where they had motion-controlled cameras, tables, and benches synched up so they could do the only ever forced-perspective shots with moving cameras ever really used.

Everything since then went digital in the following years, the technique was never really used again.

In the Hobbit films, they had to lean more into digital because they were in 3D, so forced perspective shots wouldn't work.

The fact that Jonathan Rhys-Davies is 6'3 actually made it so shots with him and the hobbits could just be normal shots. They needed the camera tricks only when he was with others.

They replaced the hobbits with doubles who were little people on some scenes.

Not that I disagree with what you're saying. I'm pretty sure most of it was camera trickery, but my earlier comment was more about three specific scenes where doubles (halves?) were used.