This is a really annoying limitation that I genuinely don't understand the need for. It seems a really irritating place to throw up an arbitrary wall. If they're going to let me use the bulbs with their system in the first place, why cripple them by not bridging them to HomeKit with whatever level of functionality they already support them for?

I bought two cheaper bulbs and won't buy any more of those because of this. So I guess if the reason is "money grab" i have to grudgingly admit it was successful.