It does help with loading sometimes, but CPUs are for computing so it really helps with either gaming or music/video editing, rendering stuff that sort of thing. You don't need SSDs for faster loading, a 2 or 3 HDD set up in RAID 0 is much much faster than a single HDD, and HDDs are way cheaper $/GB than SSDs.
HDDs in RAID 0 does NOT help in loading.
Loading is dependent on the access time instead of transfer rate. Raid 0 only improves the transfer rate, FYI.