Caching takes care of all our concerns regarding small file access and so on, and also swap. However, this is of course only possible if we have enough RAM to cache things in ;-)

The few magnitudes claim comes from something called write amplification. The native flash block size is some 256kilobytes. Writing a 4k sector (as the OS often does) causes the emmc/sd to erase a new 256kb block from a pool of spares, (if there isn't one already erased available), read in 256kb, modify 4k of it, write it to the new block, put the old block into the spare pool.

Thus, a 4k write request from the OS was turned into a 256k read, 256k erase and 256k write. 256/4 is a factor 64 already

On the emmc/sd, 256k physical blocks are linearly mapped to 256k logical blocks.

With nand we can do it smarter, while the erase size is huge 256k, an erased block doesn't need to be completely written in one go. We can write 4k and fill in the rest later. We have the cpu to map blocks of 4k nonlinearly onto the 4k flash, so that even if the filesystem wants to update a table at the start of disk, a file entry in the middle, and some data elsewhere, we turn it into 3 writes into the same block.
This is roughly what modern SSDs also do, and they have ARM cpus and 64 or more megs of ram to do it, which explains why there are no sd cards doing clever stuff.

Now, normal filesystems are optimized for rotational media. There all kinds of non-sequential access becomes slow. So, they operate on the idea that data is read more often than written, and thus spend alot of effort on placing the data optimally, so that related data is close together. This is exactly the opposite thing you want to do on a flash based device.

nilfs2 and logfs, however, are very good for performance on emmc/flash
(and ubifs, but that can only be used on nand)

So yes, if we can use LogFS, and if we can have swap on its own device, or someone writes a new loop block device specifically to optimize swap on flash, having non-media system files on emmc would be doable..

Without logfs though, I suspect we get more of all sortsof "stuttering" people cmplain so much about even now