Shrugs
The curse marks offer like...the lowest tier of power boosting that exists in the series. Capping off at around the boost of a version 1 Chakra Cloak at 1 maybe 2 tails if we stretch it.
Chakra Modes
Sage Mode
Tailed Beat Cloaks
etc.
At the very least most of these offer a power-boost comparable to 4 tails Version 2 Cloak, in some way, shape, or form.
Well, to be fair the Curse mark does outclass one-off power-up items, but I think it'd need a version three to actually stay relevant. Just staying as an inferior Sage mode will leave it little room for flexing in Shippuden when it goes up against the real deal.