Does an SSD need DRAM, and does DRAM-less matter?

It depends on your use. Specialist-community consensus is that most everyday users won't notice a DRAM-less design, especially modern drives that use Host Memory Buffer. However, DRAM-less and QLC-based drives tend to slow dramatically once their cache is exhausted during sustained large writes, so heavy-write users (video editors, frequent large file transfers) are steered toward DRAM-equipped TLC drives like the Samsung 990 PRO or WD_BLACK SN850X.