Every full time job I've had I've been issued a MacBook and step 1 of setup was "install Firefox or Chrome".
Safari is one of the few things that truly outright blows about the Apple ecosystem.
It's as fast as Chrome and Firefox. (Firefox is curiously sluggish on the Mac, even when the latest Quantum improvements.)
Sure, it tends to lag behind when it comes to adopting certain newfangled web technologies, but it supports everything that's important (even web workers now? I think?), and it's super stable.
I use Chrome for web development, though, because of the built-in dev tools. (The tools are pretty gnarly for 2019, but they get the job done, for the most part.)
It doesn't matter how nice the privacy features are, when a user encounters web site after web site that doesn't work right in their browser, they eventually each out to a more technical friend that recommends trying browser X. When browser X fixes their problems, they never return.