Agility.
It’s really law of physics. The bigger you are, you must be exponentially stronger — in relation to your own weight — to handle the same G powers for example when turning.
Going the length of the ice is different. Supposedly there is a breaking point. I don’t know what it is, but the optimal skater can be taller than the optimal runner. In short, the taller you are when you run, the longer strides you can take and that is an advantage. But — you will also be in the air for a longer time, while basically having your feet on the ground the same time as someone shorter, and this means that you through your foot must get more power into the ground than someone shorter. This is really why we don’t see anyone 6’6 winning the 100/200 meter sprints. The amount of force your foot/calves etc can get into the ground during isn’t enough to get someone 6’6 running as fast as someone 6’2, or whatever Usain Bolt is. But when skating you have your blades to the ice longer which moves up the breaking point. It can be around 6’5-6’6 in terms of top speed I guess.