Wild West will be here in a minute to write a 10 paragraph essay on workstation PCs, just give him a min to drink his coffee.
I don't drink that vile swill. Can you imagine how amped up I would be if I were?
RIPing wouldn't be something that I would consider to qualify for a true workstation rig. What some people call workstations, I would not. The only caveat here would be is if that same rig has to do multi-tasking (one rig to rule them all type of thing). For a lot of reasons, I prefer towers over laptops for main workloads, but to each their own. I have run production on a gaming laptop, so it's not impossible, the longevity of said laptop would depend on it's specs. Some can last longer under higher workloads then others.
While I have used a gaming rig and most people on here suggest gaming rigs for things (in general mind you), keep in mind gaming rigs focus on different computing conditions then what would necessarily be important for our workload. In general, not necessarily specifically what's being talked about in this thread.
which means why do you need a laptop if it's plugged in all the time.
Space, as in smaller footprint. When I was running said laptop above, it was always plugged in and I had actually removed the battery, so that constant charge didn't kill it. It was on a battery backup, so it didn't lose power instantly either.
I think there have been some that have used NUCs (I would say a Mac Mini would qualify as well) for RIPing as well. Now, they aren't running Windows. I think can even get Caldera on a Dell NUC running Linux as well from Caldera. If smaller footprint is a reason. My son has a NUC that I put together for him. I actually quite like it. Specific focused single use case it does great. Again, not running Windows, his runs Neon.