Not sure what is happening to the Blues.
Every capacity upgrade will drop the TBW (roughly halving it) in each size segment - so a 1TB will have the TBW of the next gens 2TB
(They use chips with double the density whenever they can - so a 1TB vs a 1TB would have half the chips, half the life. If its just more layers on the same chip number TLC/QLC, the change isn't as large)
NVME budget drives are going DRAMless and it's not a huge issue since they have HBM (and it's improving steadily)
Second link on it - Anandtech
DRAMless on SATA, i'm not keen on. Without a buffer those random writes are gunna get really poor, and in theory it could hurt their lifespan without something to buffer up the small writes.
DRAM cache seems to be slowly dissapearing from consumer drives. I wonder why.
HBM solved the issue on NVME - it uses system DRAM instead, and with modern DDR4 and DDR5 systems that little bit of HBM cache is MASSIVELY faster than the internal LPDDR3/4 was
As for SATA SSD's? Probably because they're now the budget segment. NVME has existed for a very very long time now, and even cheap SSD's can saturate the SATA III interface easily in basic read/write.
The HMB TL;DR summary is that the DRAM cache was so small it was only ever really used to buffer the file tables anyway, having them in system ram the OS is aware of sped things up even more.
Write buffering seems to be relegated to the OS, and you just hope they do it well.
This is of course from an NVME drive, but as you can see working with a smaller amount of data at a time going HBM/cache free was faster - if they view these as budget drives for smaller writes at a time, they'd possibly be genuinely better off without the DRAM.
(It's not like you can remove the DRAM from an SSD to test, but you can disable HBM to test as a somewhat valid comparison)
Interestingly this drive only used 38MB of DRAM - but look at the performance gain when dealing with huge amounts of files, since it meant there was no delay in knowing where they had to be written to the drive
If you think of the average joe out there, they genuinely would write less than 2GB at a time in almost all circumstances
The most interesting part of that anandtech article is that the difference between HBM on and off is there, but FAR smaller than the difference between the 240GB and 480GB model - getting the smallest size of ANY SSD series means you're getting the least amount of flash memory and performance and endurance are GARBAGE. If you're after small sizes, get a last gen drive where it's not the baby of that product stack