UK gambling tax isn't on the consumer anyway, it's on the gambling organisation, which in the case of loot boxes would be the game publishers(All gambling winnings are tax free), so yeah not sure why that would be opposed in any measure given only massive gaming companies really have reason do this big loot box economy stuff (But that's not really what this seems to be in any sense given taxation is only a small tool of regulation like this which is primarily intended to protect children & vulnerable people).