how so, use RY as an example, they payout .87 I believe per quarter or close to 50% of their profit. As those who are enrolled in DRIP plans they are purchased on the open market (haven't checked lately) but they don't issue out new shares for DRIPS they are bought on the open market. Whether you DRIP or not with RY there is no dilution or fear of not having funds to pay out as it all comes from profit. 

As for those companies that issue out new share from their treasury now you can discuss dilution. As for discounts offered on DRIPS from certain companies it ensures you maintain a healthy client pool.

Every person like the author and some other posters have stated it is up to each individual investor to determine what is best.

Oh and the article carries a link to companies that offer the DRIP, discount yes or no, whether bought on the open market or from their treasury.