Companies did this because it's cheaper and easier to implement.
Old game (cRPGs) didn't do it because, usually, no voiced line that use the word his/her.
There will be extra cost to record extra line exclusively for another gender.
It's cheaper and smarter just streamlined dialogue lines into one, instead of recording twice just to call you him/her, so they use "them" or avoid using it altogether because #somebody always going to notice when it used "them" too often.
Except many of the companies that do this still have gendered dialogue. Sometimes it's tied to "Body Type" sometimes they have a selection for what gender you are (That is separate from body type, genitals and voice).
Meaning they still go through all the effort of making gendered differences, but still call it "Body Type A" and "Body Type B" instead of Male and Female just because non-binaries are afraid of said terms.
Historically in cRPG, gender never matters, what matters is your background or skills, that define your character.
Actually, it has mattered on occasion. Namely regarding what romance options you have. Some have also had equipment that was gender locked (Ones that were trying for more realism as opposed to the whole magically size altering nature of what we're used to - Whereby you can loot some armour being worn by a Half-Orc and then equip it on your Halfling and it fits just fine... Rather than being like that scene in LotR where Gimli puts on a human sized chainmail which trails onto the floor)
Ironically, gender defined romance options has actually fallen away while gendered dialogue has increased over time. More modern games have romance options being playersexual, whilst also making more of a point to include gendered dialogue.
There are exceptions of course, Rogue Trader for example is more classic, with gendered romance options and lack of gendered dialogue (You are always "Lord Captain" and never referred to by pronoun)
Your background in Baldur's Gate 3 stays relevant the entire game, your background in Mass Effect matters once or twice at most in the entire trilogy.
Your background in Baldur's Gate 3 is never relevant. The actions for your inspirations are largely irrelevant fluff. Thus arguably background in ME means more because it's directly referenced 3 times and determines 2 missions. While in BG3 your background is never once referenced, not even a single fluff dialogue option (There are class dialogue options but no background ones)
