On 31 December 2017, the IRS clarified that § 1031 does not apply to crypt-crypto trades. It did not say § 1031 applied to crypto-crypto trades before then.

The article you reference says "traders still may be able to argue that their transactions undertaken in 2017 and prior years were not taxable under the Section 1031 like-kind exchange rules," but that "the application of the like-kind exchange rules to crypto transactions is far from certain" [1, emphasis mine].

[1] https://www.coindesk.com/owe-irs-crypto-crypto-trades/