Sorry - I can't agree at all. It's a numbers game. Where there is success those who feel they have a chance will follow. Black children see black success in sprints so try sprints by the bucket load- where there can be great rewards if they are successful. The vast majority won't make it but lots of competitors mean lots more chance of some great talent emerging. The bigger pyramid means it's more crowded at the top and more are competing for the prize.
If white kids want to do other things they won't have success at track. We see lots of fast white kids in team sports but they don't want to do track with hours of training and very little socialising in comparison to team sports. And (as I see here in Australia) there is no great need to rely on "track" to have hope for a decent future. Some people may be doing it tough at the moment because of our house prices but there is no endemic poverty here what with free medical and a healthy social safety net (although I admit we've a ways to go in solving health issues with our outback native people).
Unfortunately lots of white kids don't have the drive because they don't need it to have a great lifestyle - often "success" means inherited wealth, certainly here where I live. e.g if a typical 3 or 4 bedroom home in my area is worth $3 to $4 million and there are 2 children who'll inherit it, they could virtually stay there and sponge till the parents die and be set for life. Often though they get a nice tertiary education and follow into the profession dad (and often mum too) are in. Wealth begets wealth as privilege begets privilege.
Audrey LeDuc has proved she has what it takes and will get selected - as should be the case. No system has held her back so why would it hold other white kids back? If they run well enough they'll get their chances - Wariner is a good example of that. Nick Macrozanaris had a chance especially after his banner year of 2003. Nick was Canada's all-time number 3 at the time.
Jarod Connaughton, pretty fast, was the next best white 100m sprinter Canada's had but he's about number 25 all-time.
An Irish poster the other day moaned about Adeleke being forced down their throats !! she just ran nearly 2 seconds better than all the years of white athletes have run 400m and gave the Irish people something to cheer about in the 400 individual and mixed relay/relay events. Why would she not be celebrated? Coaches saw her commitment and physical characteristics years ago and have shown their trust in her was well placed. Mawdsely is next best and is certainly of mixed race - this is Ireland's chance for a success in races that aren't middle/long distance.
Now, here in Australia our Afro-Australian sprinters have not beaten our best "white" sprinters - why? in part because there isn't the need to make a living out of track here. An education takes care of business and in most cases they will adopt our cultural view that athletics is fine till life gets serious and you get a career. Jana Pittman (2x world 400H champ) even while training was being asked medical questions by her mother between sets in order to graduate medical school, Paul Narracott (beat Carl Lewis over 60m and finalist in 1983 world champs 100m was studying at the time to be a dental surgeon), Rohan Browning will most likely practise as a full-time lawyer as of next year. There are tons of others.
My point is that something you can do well which entails fairly moderate financial layout will go a long way towards incentivising those for whom little else is available in life or is behind the 8 ball from birth