Vitalik was a big blocks supporter for a long time. I saw this post as a 180 as well.
"Now I personally can see that it’s not axiomatically true that doing nothing is safest, especially in the context of a changing environment (for example I continue to believe that Bitcoin’s failure to raise its blocksize by a significant amount in 2016–17 was a travesty and a great violation of many people’s expectations of the protocol, and one that led to more total losses due to excess txfees than the amount lost in the MtGox hack), but this is the argument that you need to be arguing against."[1]
"Now I personally can see that it’s not axiomatically true that doing nothing is safest, especially in the context of a changing environment (for example I continue to believe that Bitcoin’s failure to raise its blocksize by a significant amount in 2016–17 was a travesty and a great violation of many people’s expectations of the protocol, and one that led to more total losses due to excess txfees than the amount lost in the MtGox hack), but this is the argument that you need to be arguing against."[1]
[1] 12/26/2018 https://medium.com/@VitalikButerin/he-imagines-a-world-in-wh...