That doesn't look like your best. Here's the blog you refer to[1]:
https://optimismpbc.medium.com/
Imagine I came to it around the time of the switchover. Which of those headlines looks like it's alerting me that my transaction history will be gone?
Here's the Optimistic ethereum site:
Where is/was the blaring warning about missing transaction data?
Here's the Twitter page[1]:
https://twitter.com/optimismPBC
The only pinned tweet is a cute meme about the whitelist change, nothing to head off frustrated users wondering where transaction history went. (I don't know how to link a historical post in context but I can assure it was not evident on the Twitter feed why I was missing transaction history, and there are no such warnings before.)
The only reason I even got on the Optimism Discord is because none of these places had any information! And then, even when I went to the Discord, and go to #announcements, and look at what was being announced in the runup and release, the loss of transactions still isn't mentioned! [2]
Maintainers talk about the upgrade, to be sure, but not this implication of it.
So no, I don't know how can justify the claim that you made a serious effort to alert users.
[1] Linked from the community tab of https://www.optimism.io/
[2] https://discord.com/channels/667044843901681675/754090866435...