Yeah Blue and God being anything near something special died down after Freeza, Hit, Gohan, and god knows who else caught up to Blue without Angel/GoD training and two faggots who'd have gotten stomped by Zamasu surpassed MUI tier by wishing on a piddly Dragon. But I'd support the idea of #17 being 3 tier rather than Completed Blue tier simply because Dyspo was treated like a bug by Blue Vegeta and Goku and #17, despite not needing to worry about conserving stamina, couldn't defeat him quickly. Dyspo being someone who'd give SSJ2 a lot of trouble and would be at a disadvantage against SSJ3 makes perfect sense.
The only real problem in assuming God forms were out of the equation when Goku made that statement about #17 having nearly caught up to him is that Vegeta was included in the statement as well, and Vegeta has no SSJ3 equivalent - he is equal to Goku in all forms except SSJ2, which is between 3 and God tier through copying and improving Trunks' Full Power SSJ2 form or some such nonsense.