I think for some there was a genuine interest in seeing people with the necessary skills (or at least the willingness to learn and improve) being given opportunities to try. I also think in some areas, particularly the arts, there was a desire to see more 'original content' and get more stories of different types and perspectives told. This is likely why the movement started gaining momentum, like most LGBT incentives, and why people are now left with a sour taste in their mouths: their desire did not transpire and has been shaped into something horrific and unfamiliar.
This was rapidly coopted by the same types that tend to destroy everything. Opportunists, money chasers, and groundless nepotistic hires ran rampant. Hateful sods took it as an opportunity to be exclusionary rather than inclusive. People with actual talent and promise were abandoned in favor of colors and pronouns and sexual preferences.
I think several other factors also bled into this - as is often the case - like businesses taking the wrong cues and lessons when one thing worked and another didn't, or likeminded heads in certain industries forcibly injecting their thoughts and opinions on what humanity should be onto humanity instead of just offering goods and services. I'm sure some businesses have absolutely taken this as an excuse to hire cheap labour in some fashion but funnily enough, in places like Hollywood, the arts and entertainment, and politics (where I think some of the most vocal reside), the DEI hires are money-hungry hacks with a student debt for a non-major that needs to be paid off and a belief that they're God's gift to the world and should be adored for merely breathing.