Do you know where your predecessor may have seen that? I've never seen anything suggest that SAN attached storage be recommended, just RAID (1+0) levels. The only recommendation regarding SQL server that is "against" is having your pollers and SQL box separated by a WAN.
Requirements: Requirements for SolarWinds SAM
I'd find it very odd for them to recommend against using a SAN for storage, especially as the I/O throughput for SANs is usually far better than local disks. Maybe your predecessor misunderstood something?