They may very well be at a competitive disadvantage, but unless something magical happens to communicate to someone that fact as "having contributed to failure" or "at the margin, caused the failure", that disadvantage doesn't translate into anything that helps either discriminated against individuals, nor does it help improve cultures that allow or encourage discrimination.
The individual or even group decision-making (with regards to not just company goals, but to lifestyles and associations) means that things like that end up as a wash. Make it more concrete:
28 year old founder decides to pass on excellent 47 year old programmer. What does that do the founder's life or company? Let's speculate on some possibilities:
- It does nothing, because even though the older developer would have been better, their level of experience wasn't even necessary to do the job well.
- The business winds up marginally less profitable, but still succeeds.
- The business fails, somehow, because at the margin, missing out on hiring that older developer somehow started a chain of events that could have been prevented if said older developer were hired.
In all cases, the founder goes on to find another job, makes plenty of money, is able to surround themselves with the type of people they'd rather be around (people their own age) and never is even aware of any impact on anything. To that person, it was just "didn't hire someone, something happened or didn't, life went on well, and founder was still happy, ultimately."
What I'm saying is that the "disadvantage" and other related theories start sounding like a secular version of Karma; people use them as a way to tell themselves there will be justice (not that you're necessarily doing that, I have no idea), when in truth it's likely there will be none.
You can try to "prevent" the discrimination through your own actions, which is by no means easy (https://medium.com/@spencer_th0mas/dealing-with-ageism-in-te...), but as the article makes clear, even in egregious cases, it's hard to prove or do anything about. Look how long we've had these various kinds of incredibly well-intentioned anti-discrimination laws, and look at the success rates on the suits / how often they're brought. The results are terrible. It's just too hard to prove.