I don't know whether it's still the case, but at least in the early days, it was common for RAM chips to be one bit wide, so e.g. an 8-bit computer would install them in groups of eight.
Not really. It depends on the way the Family designers envisioned a certain system. And what the use case in terms of memory needed was. Early RAM chips where all static and organized as x1, x4 or x8. Intel's 1 KiBit Ram was available as 256x4 as 2101 or 1024x1 called 2102.
The 2101 was housed in a 22 pin package, while the 2102 only needed 16. Due to the smaller package these chips could be offered for less, and building systems was even cheaper due the lower pin count. On the backside, it takes 8 chips to get a byte. Applications that need only 256 bytes or less are better off to use nibble wide memories, as with the 2102 only two ships where to be soldered. And while each might be a few percent more expensive than its x1 counterpart, cutting the BOM down from 8 to 2 chips was quite a saving.
Motorola went even a step ahead and made its 1 KiBit chip 6810 byte-wide. Thus, embedded systems with a need of 128 bytes or less could be made with just a single 24 pin IC.
MOS went with the 6550 nibble wide - again to enable small systems at low price - the 6500 was meant to be as cheap as possible.
I notice some chips were four bits wide.
For a short time - and on static RAM - they became the majority, as they allowed to cut down on chips needed. Keep in mind, back then designers didn't just fill up the address space and see if it's needed or not. Also, nibble wide chips could be used in 4 bit as well as 12 bit systems. So it might be a sweet spot.
but only a handful eight bits.
Early on yes, but around 1980 8 bit wide static RAM became the standard. See 6116, 6264, 62256, etc. Much like with (EP)ROM static RAM didn't need multiplexing, thus 8 bit wide is the most simple cost effective design - as long as the memory need can be satisfied by one IC.
And before you ask, 4 bit wide DRAM were a special case. They where especially popular with 256 KiBit RAMs. When organized as 64 Ki by 4 two could be used to fill the whole address space of an 8 bit micro. So similar organization, but different reasoning.