There are still places running analog (0 to 10V, polarity depending on manufacturer, 1 signal wire per channel) controls systems, it was a perfectly good standard back in the day and was used in systems having well over 100 channels of dimmer, sometimes the controls were digital, sometimes analogue (Banks of faders, diodes and switches).
You cannot call yourself an operator until you have run a busy show on a Strand AMC or Threeset, and I know folk who say the same thing but for the Grandmaster (Direct power rheostats in series with the lamps, lots of mechanical linkages and gears, very steampunk, bits of wood, elbows, knees and feet were required to run a complex crossfade).
There is at least one grand master still in (somewhat limited) service!
Dimmers inside the auditorium volume are not popular due to the combination of fan and buzz from the suppression chokes, also of you have them all in one place there are more opportunities to leverage load diversity, I can have 200kW of lamps on a 100kVA feed because not everything is on in any one scene. Also, dimmers were not always exactly what you would call compact.
At the small venue end I remember one place that had a big ammeter on the front wall of the control room, scaled in amps up to 60, and minutes/seconds above that (Hand written scale), as long as you did not exceed the 60 amp rating of the incoming supply fuse for more then the number of seconds indicated on the meter everything was fine....
Seriously, no squint is down on LED, we use them, they are a great tool for the right job, but they are NOT even close to being a sub for TH in this application.
regards, Dan.