the data layer does not become useless
with the server-side implementation we do not have in our taiwan cellphone number hands a tool that bypasses the various GDPR and other legislation dedicated to privacy, rather it allows us to better manage the information that passes through our website before being sent to third-party suppliers.
Good question, but the answer is no. We need to start step-by-step measuring each server-side implementation and comparing it with the one we track on the web. This way we can observe the differences in the data collected.
Also, another reason not to switch to server-side implementation only is that not all the providers we use are ready and have the tools to migrate to server tracking. It will take time and surely each one will offer the right tools (tags, templates etc.) but at the moment the list is still short.
Let's say that the advice is the same that is still given today on the implementation of GA4, that is, to run the tracking of Universal Analytics and Google Analytics 4 in parallel. Similarly, today the advice is: start as soon as possible, but with a view to parallel tracking to get to know the tool, master it, and measure the differences between the two environments.
If you want to go into more detail on the topic, I wrote an in-depth guide on the subject which you can find here .
Conclusions
Humans are not immediately inclined to novelties, especially when it comes to technology. The brain is neophobic and afraid of taking new paths. In fact, it needs something or someone to push it to change.