That advantage you see is an important one of availability. Here are a few more advantages for reloaders:
1. It is much easier today, and for a while, to find SPP than LPP and they are usually less expensive...so now you can find them and it cost less.
2. When importers enter the market, they usually start with SPP...due to the larger market...so that increases availability again
3. SPP are easier to set off than LPP. Using Federal primers in my competition revolvers, I can go with a lighter mainspring when shooting SPP .45ACP than when loading LPP .45ACP in my S&W 625
4. SPP are easier to fully seat than LPP. That is just based on physics...an amount of force applied to a ram of smaller area will transfer more force than that same amount of force applied to a ram with a larger area