It's not because of the Mac - it's because of the iPhone. The reason Airdrop didn't work between the 2 devices initially is because of how the iPhone handles Airdrop. The iPhone handles AirDrop via Bluetooth 4/LE b/c of battery life issues. The iPhone uses Bluetooth LE in order to contact the other iPhone/iPad and setup the transfer in info, but the actual transfer is done via Wifi. Bluetooth 3.0 was a severe battery drain - it didn't allow the device to allow the Bluetooth chip to enter a low-energy state. Think of it like wading vs. swimming. BT 3.0 made the device swim to connect to other devices with purpose. BT 4.0 allows the device to 'wade' and detect other devices but not necessarily connect to them.
The Mac limitation really isn't a 'Mac' limitation, but an iPhone one b/c while the Mac's battery may not drain fast enough with BT 3.0 enabled enough to concern Apple, the iPhone's battery - which isn't that big anyway - would drain quickly.
But that doesn't address one glaring difference between AirDrop and Handoff - Handoff is, in theory, a seamless transition that shouldn't involve the user - the devices recognize each other on their own, so whenever you want to pick up a task that has been started, you can; Handoff requires "always on." Otherwise, what's the point?
However, with AirDrop, both with Mac-Mac and iPhone-iPhone as currently implemented, the feature has to be enabled/clicked everytime a transfer is to be initiated. Bluetooth (or Wifi) isn't always listening. In fact, Bluetooth on my iPhone is usually off, but I can tap on AirDrop, which activates it, and then I can turn it off. I guess I'm just annoyed Apple isn't implementing a WiFi based AirDrop on the iPhone when it doesn't always need to be on in the first place.