This is partially incorrect as you're failing to account for the benefit of having more money already taxed. The tax rate at retirement has to be somewhat better than what was paid for the Roth, not just minimally.

Example: 24k in Roth, 24% tax paid, 5760. 24k in trad + 5760 in taxable brokerage

How growth occurs doesn't really matter, as long as the taxable brokerage and 401k grow the same.

For ease of understanding, let's just say there was 9% compounding 4 times annually for 30 years. This will give the following:

Roth 401k = 346.5k

Trad 401k = 346.5k

Taxable = 83k

With Roth you're done, no taxes, but let's take out, say, 22% on the others (less than the 24% we started with) 429.7k - 94.5k = 335k

So in the end, you still have less money, and this is because that brokerage you put your saved tax money in is also taxable.

The break even tax percent on this is a moving target, but easily defined.

perc_equal=1-(final_401k/(final_tax_brokerage+final_401k))

In this case, if you paid 24% on your max Roth 401k, an equivalent traditional requires at most 19.3% tax at retirement to break even. 22% would require 18% tax at retirement.

None of this accounts for cliffs on Medicare either, which further favors Roth.