Some languages have gendered words as a fundamental grammatical aspect of the language (though since this language aspect evolved out of earlier grammatical distinctions that had nothing to do with “gender”, frequently the gendering of words is kinda random). English doesn’t have grammatical gender, and it has a relatively small set of words in its vocabulary that are specifically gendered. The argument goes that the use of some of this vocabulary is harmful, and that it’s easier to try to move away from using the whole class of gender-specific vocabulary words outside of actually gender-specific scenarios than it is to try to define and keep track of which gendered vocabulary words should be discouraged. Words like “motherboard” are collateral damage of this broader effort to discourage use of terms like “mothering”, which can be used in English to mean both “being mother to”, but also in a metaphorical generic sense as “being responsible for and looking after”, even of things that are not children, and is discouraged in favor of “parenting” or “caretaking”, which have the same implications but without the gendered aspect.
If the objection were to parenthood, which is to say if nurtureboard or parentboard were similarly offensive, then I agree this would have been a stupid stupid choice.
The problem is that you had a motherboard and daughter boards, those were the accepted terms, and never fatherboard or son boards, never parentboard or child boards. Why were they gendered female in the first place?
Because they had “female connections,” which is to say their use is in plugging pins into their sockets.
Obviously that is a sexual analogy that did not age particularly well, this idea that a motherboard is the motherboard because you shove stuff into it. So people started replacing with mainboard because it makes more sense...
>Why were they gendered female in the first place?
well, for this context, it's called a "motherboard" because "mainboard" was already a thing. Motherboard was to distinguish at the time how this new board can be expanded upon by plugging in ports. There was no real malice here, it was just fancy marketing term that stuck.
Ultimately, we're humans and we try to anthropize all kinds of things in life to make them "feel relatable", be it animals, boats, hurricanes, or yes, computer. so that extends to our language as well. Especially in marketing where the goal is to make customers feel good and close the sale. There may be a conversation on WHY we do this, but starting that conversation on the foot of "well people just want to be sexist" won't get us anywhere.
It's more likely that it's a similar naming to mother lode, i.e. the motherboard is the central source of the computer and everything connected to it is a child that hangs off of it.
