Get a decent large enough SSD boot drive for system OS and apps.
Separate drives also helps improve performance because they are not queueing and waiting.
Use RAID for large media libraries that won't fit and be accomodated by a single drive.
After all you have options like $200 1TB 10K WD VR t oday, or 4TB Seagate, both are 180MB/sec and high performance.
Or there are your PCIe SATA SSD storage devices ($$$) of 960GB (and there are people using a pair for 1,8TB and highest performance).
"Perhaps?" No, you really never want to put all your eggs in one basket. Redundant, duplicate, sets and methods. Even RAID6 arrays - I've seen where two such were used.
You do not need or want an array for the system boot drive though.
You almost have to install and plan to keep a non-array system drive today and then clone the system onto the array. Arrays can't have a recovery partition.