As long as there isn't any other stuff on 2.4 GHz, it can indeed be beneficial.
But if there are any legacy 802.11 (especially pre-802.11n) or non-802.11 transmitters nearby, it can be catastrophic for throughput, both because you need protective measures when transmitting (so that older 802.11 versions can reliably detect your transmissions as occupying the carrier) and because some of them just don't cooperate well with 802.11 at all (e.g. Bluetooth, which will just happily transmit over 802.11 without any regard for CSMA/CA fairness at all).
But if there are any legacy 802.11 (especially pre-802.11n) or non-802.11 transmitters nearby, it can be catastrophic for throughput, both because you need protective measures when transmitting (so that older 802.11 versions can reliably detect your transmissions as occupying the carrier) and because some of them just don't cooperate well with 802.11 at all (e.g. Bluetooth, which will just happily transmit over 802.11 without any regard for CSMA/CA fairness at all).