I have quite a few brokerage accounts and quite a few ETFs. I reinvest manually and also use DRIP for a few of them.
The article does present the situation, but is not quite correct on everything. Each broker is different in the way it buys additional shares for a DRIP. For instance, Fidelity actually buys shares the day the ETF goes ex-dividend in anticipation of the dividend. TDAmeritrade buys the day after the payable date.
There is a bogleheads discussion on this that you should check out, too: https://www.bogleheads.org/forum/viewtopic.php?t=87742
and here is a good one with some data of reinvested prices for a bond ETF:
And if one manually reinvests the dividends, I think one will find that they do not stay on top of reinvesting in a timely fashion, but let the money sit in the account a few days or weeks. This is probably not good for bond ETFs. However, for equity ETFs, the prices go up and down. I'll bet that one can pay less a few days later in many instances than the article would have you believe.
The example of IST, an ETF with an average daily volume of a minuscule 4000 shares, is a total joke. One should not even bother with owning such an ETF in the first place. 4000 shares? C'mon!!