Not actually. The CPF Board is describing the CPF LIFE Basic Plan rather fairly here, I think.
First of all it's important to understand what they're saying. They're saying the Basic Plan payouts will eventually sag a bit(*) if you live long enough due to the way bonus interest crediting works with that specific plan. That's absolutely true, and it's true even if you have $1 million in your OA+SA+MA in any allocation. They're not saying you won't earn maximum bonus interest, even for the rest of your life. (You very well might!) They're only describing the CPF LIFE Basic Plan's payout behaviors, exactly as they wrote.
The way this works according to current bonus interest crediting rules is that, once your Retirement Account falls below $40,000 (at the very latest), the bonus interest
credited to your Retirement Account starts to fall below the maximum attainable $900/year. If you keep at least $20,000 in your Ordinary Account then you won't lose all bonus interest crediting into your RA, but you'll lose much of it from the $40,000 mark. Specifically, you'll eventually lose $500 out of the maximum possible $900 bonus interest per year.
The loss of the bonus interest at some point is why the Basic Plan has a quirky "burble," where the monthly payout goes falls a bit and stays down after a certain age. This is unavoidable with the Basic Plan because some bonus interest loss in the RA in unavoidable, assuming you live at least long enough to see it.
If your MA+SA+OA+RA is maintained at $60,000 or more, then you'll still earn maximum possible bonus interest. It's just that the bonus interest will start to "stick" in your SA and potentially also MA as well, depending on your balances. It's only OA's contribution to bonus interest that credits to RA, plus RA itself of course.
The CPF Board explains these various bonus interest crediting rules
here.
(*) The payout amount won't sag quite as much if you maintain $20,000 in your OA, but it'll still sag a bit.