It's a problem of unit volume which can't be fixed on teamgames unless you make people have a smaller popcap.
Few metas had been more reliant on medium (for teamgames) spam than TD + artillery.
I think what I would try in regards to team games, is reducing the amount of resource points. Not necessarily the points as a whole as that requires rebalancing and redesigning maps but the points that generate resources. Add in more of the flavor points like medics and repair stations and those watch tower points. Add some variety and reduce resource income at the same time. It'll decrease unit turn around but those units will be a bit reduced in number. The action will remain high but armour will be a bit less expendable