An eight-bit processor like the Intel 8008 addresses eight bits, but as this is the full width of the accumulator and other registers, this could be considered either byte-addressable or word-addressable.
32-bit x86 processors, which address memory in 8-bit units but have 32-bit general-purpose registers and can operate on 32-bit items with a single instruction, are byte-addressable.
If the 386 and its successors had used word addressing, scientists, engineers, and gamers could all have run programs that were 4x larger on 32-bit machines.
When computers were so costly that they were only or mainly used for science and engineering, word addressing was the obvious mode.
As it became cost-effective to use computers for handling text, hardware designers moved to byte addressing.
Some systems with word addressing, such as the PDP-6/10 and the GE-600/Honeywell 6000 series, have special mechanisms for accessing bytes efficiently.
[3]: 2-85–2-89 Programs took advantage of this flexibility: those not needing lowercase letters used the limited character set of 6-bit bytes for efficiency; most used 7-bit ASCII, packed 5 to a word with one unused bit; and the C implementation used 9-bit bytes because C requires all memory to be byte-addressable.