I'll give you an example. At a previous employer, We used Google Analytics. We paid for Google Analytics. I feel positive that as a mid size company, We shouldn't have paid for Google Analytics. The free product with 50 events in GA4 should be plenty for us. But why do we use Google Analytics in the first place? Because everyone uses Google Analytics.
I agree that sometimes Salesforce might be a good idea. However, it should be a part of an overall strategy, not just because everyone does it. This kind of deliberate tooling strategy is difficult though because the way Google Analytics or Salesforce works from what I understand is make marketing folks feel they are specialized in Google Analytics or Salesforce so they feel like they have to keep using it or their skill will become useless.
It is like resume driven development but for the whole business.
It's like this for most software, but as a salaryman it's better for you if you use the common software. If you have an interview you can now say "I know how to use the thing that most people use" instead of "Actually we had an inhouse system so if you hire me I need to be onboarded for 3 months".
I got hired to my 2nd job in large part because I knew how to use Broadridge Paladyne (back then it was pretty good if you got over the pretty bad UI/UX, by today's standards it's not great).
„Everyone does that“ is definitely part of decision-making process almost everywhere, but I personally have not seen companies where it’s just a cargo cult rather than a reasonable strategic choice. The obvious benefits are that it’s easier to find implementation partners, the costs are predictable and your users may already know the system, so you won’t have unnecessary friction in your ops.