So does this happened because the rising adaptation of SSD or it's bound to happen after all for HDD to cutting cost?
It's competition. Every cost cutting tech gets adoption except for boost the main muggle specs like capacity. On the SSD side we have DRAMless and TLC. The annoying thing is that unless the government forces disclosure, the honest manufacturers are the ones hurt, having to start advertising "no SMR!" to differentiate, like the organic/health food products in the grocery store that have to list all the poisons they do…
Are you sure you're not talking about QLC? Current TLC drives can be pretty decent in terms of write speed and endurance.