I don't know where that thread might be, gdh, but it boils down to just a couple of basic things:
1. Many implements use hydraulics to deploy/adjust/operate some part of the implement assembly. Really important on modern agricultural implements so most ag tractors these days are set up with rear hydraulics, but it's also used on some landscaper implements. A backhoe attachment may run off the tractor hydraulics since it saves the cost of a separate pto operated hydraulic pump. And, since larger tractors operate larger, heavier implements, at some point it's a necessity. My 6' brush mower doesn't need any hydraulics, but if you have a 15' batwing mower, you'd use hydraulics to extend/retract the decks.
2. You can set up hydraulics to adjust the 3 pt linkages so you don't need to do it manually, called top-n-tilt. This is really useful with a box blade, for example, where you often need to change the settings a bit when using it. If you are doing a lot of this type of work, it can be a real convenience.
If your expected work requirements for the tractor fall into one of these categories, you'll probably want a tractor set up with rear hydraulics, but keep in mind hydraulically actuated implements will cost quite a bit more than manual ones. If you're a weekend warrior like me, well, I can get off the seat and raise/lower the box blade rippers when necessary, since I probably only use them a few times each year.
If you have some specific uses in mind, share them here and I'm sure you get plenty of more specific advice about hydraulic remotes.
