There's a recurrent type of ad that shows up every few years in the tech world - the "Welcome, seriously." ad. Maybe it shows up due to hubris or fear. It happens when an incumbent enters into a new disruptive market after startups have already started to establish themselves. The startups feel the need to respond publicly to this new threat.
Apple was the first company to launch this campaign, as far as I can tell. This ad was published in the Wall Street Journal in 1981. IBM had just announced it was entering the personal computer market. While IBM's PC didn't end up disrupting Apple's business, it did provide the licensing opportunity that catapulted Microsoft out of obscurity.
In 2015, Apple announced Apple Music. Rdio, a now-defunct startup, tweeted out this message back to Apple. Unfortunately, the ad signaled trouble, and by the end of the year, Rdio was out of business, and Pandora acquired the remaining assets from the company.
In 2016, Microsoft announced Microsoft Teams. Slack, the market leader at the time, took out a full-page ad in the New York Times titled "Dear Microsoft." It ended with a phrase nearly copied from the Apple to IBM ad, "So welcome, Microsoft, to the revolution." Three years later, Teams would pass Slack in Daily Active Users (DAUs). Four years later, Salesforce acquired Slack.
On February 4th, 2021, Substack published a "Welcome ad" to Facebook and Twitter on its blog. Twitter had recently acquired Revue, a newsletter company, and Facebook had announced Facebook Bulletin, a free newsletter platform. The jury is still out on this case.