I've had this once or twice over the years, and I don't think it is very common. Limited to situations where (maybe because of a changed ATC routing, changing winds/weather, etc.) there's a worry about arriving at the destination airport above the maximum landing weight. Better to burn the excess fuel on the ground than to circle somewhere.

I don't think it is very common, but I have experienced it a couple times over my many flights over the years.
I think once they were anticipating a much longer delay for getting released for takeoff so had put on extra fuel it turned out they didn't need.

There was stormy weather at ORD on Monday -- lightning, rain, etc., in fact we were delayed for an hour three times, so weather may have been a factor.

The choices in this situation are:
1. Return to gate to offload pax (nonrevs first)
2. Return to gate to offload checked bags
3. Burn fuel

Option 3 is usually best. I've even sat for close to an hour burning fuel.

Routine - you can find other threads about it with the search function.

Burning it off by just reving the engines for a bit is a lot better then going back and getting a truck to drain some of the fuel. You had the quick way.

Is this a max takeoff weight issue, or a max landing weight issue typically?

Couldn't they have flown lower or faster (or both) to use up some of that fuel? I'm not sure how that w:)uld work time-wise vs. just sitting with the engines on...

I wont say "categorically" but 'generally', the FARs only require a fuel dumping system for aircraft that have a lower Max Landing Wt than the Max TO Wt. Also, since fuel is mostly stored within the allowable CG range, "burning off fuel" wont usually help an out-of-range CG.
Therefore, its likely a Max TO limit, maybe due to something being added in the baggage hold that wasnt anticipated when the fueling was ordered/done.

When max landing weight (MLW) is the limiting factor, your max gross takeoff weight (MGTOW) is reduced to your MLW + Fuel Burn so it becomes a MGTOW problem.

Not if it's a takeoff weight restriction other than one based on MLW.

IF they can, you have to get a new flight plan at the lower altitude or longer route to show that you'll land at, or below, MLW.

All airliners have a MLW that is lower than their MGTOW. There are certification requirements for landing above MLW and then there's an overweight landing inspection. Generally, only widebodies have a jettison system, and not all of them have it. It would only be used in an emergency, not for convenience.