Part of the reason it was so common in the past was because rechargeable battery technology for small consumers devices was a lot more limited. NiCd was the main choice and they required careful management to keep them working well.

Also there were no real standards for chargers. Nearly every small consumer device that used NiCd batteries came with its own bespoke chargers.

Hence most small consumer devices went with replaceable batteries because they expected nearly everyone to use non-rechargeable batteries.