To be fair I think all the extra equipment people name as essentials like scales/times/naked PF etc etc are not essential at all
I'd argue that scales and shot timing essential if you want consistent results with espresso. I couldn't eyeball the difference between 14 & 15 grams of beans. But I could certainly taste the difference. Naked portafilters I agree are not essential, but are useful to spot issues when tamping. I imagine they're mainly purchased because they look great when being used.
Filter is obviously a lot more forgiving and you could probably get away without the scales and timing. But given a decent set of scales can be had for £10, and most people have a timer on their person. It seems a shame not to take advantage of using them.
You can easily have an excellent filter set-up for around £50 (decent hand grinder + V60/aeropress/French press etc.), I'd argue it's tricky to get a decent espresso set up (new) for around £6-700. At that point, spending an extra £10 for a set of scales to give you consistent results seems like a no-brainer.
Also, if you're making lattes/flat whites or whatever, you very easily mask a bad espresso with some well textured milk.
I'd honestly be surprised if someone could make a decent run of espressos without measurement of dosage and monitoring of shot times, especially the former.