> As opposed to what? What kind of distribution might you expect?
For one thing, they might have expected the result not to be dominated by luck.
> It bears literally no relationship to reality, where random massive doublings of wealth are the exception, not the rule.
I don't think this will help to control the luck as opposed to talent. I suspect the problem is in the "leverage". Having more wealth makes it easier to accrue more wealth in the future, however, the same is not true for talent. Having more talent doesn't help you get much more talent.
So eventually, regardless how big your talent can be, the accrued wealth will dominate the end of the distribution. The rate at which the wealth is accrued doesn't matter, it will only reduce social mobility.
Addendum: Interestingly, the model actually shows what we would expect for low to middle end of income distribution, that talent there is more important than wealth. Which is in line with my explanation.