I don't know why you were down voted. Yes, Let's Encrypt does verification by requiring a site to host a string on port 80. They discover the site via DNS, and

I don't know why you were down voted. Yes, Let's Encrypt does verification by requiring a site to host a string on port 80. They discover the site via DNS, and they do NOT require DNSSEC. Thus you can absolutely trick Let's Encrypt into issuing a bad cert if you can serve them bad DNS responses. This OCR issue with Comodo in TFA concerns WHOIS data, which may or may not be more reliable than unsigned DNS data. Regardless your point remains valid.