Yes I do find them unsound. Now you need ordinary people to understand the pros and cons of DMARC (SPF + DKIM). Not every one has this configured. In fact it's shocking how many companies don't have DMARC set up given the benefits.

If major providers such as Gmail/Microsoft/etc agreed to require DMARC for all incoming email senders, then maybe 5 years later we could speak about this again because then DMARC would be universally used.