Waiting for user interaction
I implemented this in version 3.4.0 (without a fuzz, well, this blog being the fuzz): When the feature is being enabled, the code waits for user interaction before actually sending events down the rabbit hole. Underneath, the browser events
wheel allow for detecting the user interaction. Actually, the weirder part is that when the feature is disabled, the
load event is added as well (which fires ... well always).
Why enable it?
Why should you enable this feature? Well, simply because the performance increases. Because the
gtm.js file of Google will only be loaded after user interaction (and only if there actually is a user to interact with things), the user experience goes up. And because the Core Web Vitals are testing for the same thing, the scores go up as well. Which is nice.
Why disable it by default?
However, note that the default is to have the feature disabled. Why? Well, this actually has less to do with the greatness of the feature (which is great and featurish) but more with the fact that there was a time where this feature did not exist and there is a time where this feature did exist. From the moment that you enable the feature, it could be that your statistics are showing a different picture than before. You are dropping robots from analytics, for instance, unless these JS-based robots also do a bit of scrolling. This could be decreasing your overall traffic in GA, while actually in real-life it would remove the fluff.
Already I've fought with Google zealots that were interpreting the documentation of Google in such a way, that it showed off their recital skills more than their understanding of real-life e-commerce. But because a merchant might be stuck in the middle, I'd rather leave it up to the merchant and their SEO experts to decide upon whether or not this feature is a benefit.
Feel free to change my mind on this.
So, the end conclusion is that this feature is way cool and that if you care for performance, you should try to enable it. For fresh shops, it should be enabled. For existing shops, you should enable it and then burn the SEO experts over it. And blame John.