I don't think multiple concentration spells necessarily breaks action economy. If you can cast both Longstrider and Jump on someone (without concentrating at all), why can't you cast Bless and Shield of Faith? I thought it worked fine in previous editions when spells just had durations.
On top of this there's a LOT of spells that I don't see any purpose in being concentration. Focusing on the ranger list because their concentration almost universally goes to Hunter's Mark:
Why is Hail of Thorns concentration? It's a single use attack spell. Not something that has a continuous effect to be focused on.
Same with lightning arrow. One use one burst of damage.
Fog at least has a continuous effect but it feels like the sort of effect that should just be dropped down and dissipate naturally over a few rounds.
And why do Barkskin and Stoneskin need concentration when Jump and Longstrider, other buff spells, not? These are defensive spells that would actually be immensely useful for druids with crap armor so they could maintain concentration on other spells more reliably!
If some of these spells didn't require concentration ranger would be in a significantly stronger position and be able to make use of their half-caster nature.
