Sure, the benefits of transformers are well known, what I meant and as you also already mentioned was, that in some low power applications capacitive droppers are actually pretty good. If you calculate your circuit well and choose oversized caps, they can pretty reliable. I actually have a dropper circuit built over 10 years ago, still works every single day. The components are absolutely oversized, if I remember correctly I used a 1kV bridge rectifier which is good for around 3 Amps and a 2000V cap as well as some big ass resistors (except the little 10 ohm input resistor which acts as an el cheapo fuse - but never did until now) inside. Sure, today you could buy an isolated PSU at the same price with smaller dimmensions
What I want to say is, everything has it's way of being usefull. You mention tubes, which I absolutely love, even though I know about theie several drawbacks compared to modern technology. But they still have their place, even if its only in our hearts <3 *sheds a tear* And yes, the live chassis are a big PITA - made the mistake to touch one at the first radio I ever looked into... bad idea.
So, basically exactly what your tl;dr states.
You are raising some very good points.
As you just said, it is only relatively recently when we have potentially had a wide availability of rather cheap, switch mode power supplies, even in rather small packages. So older electronics, has good excuses, as to why they did not go that route.
I got curious about the TV transformers, so looked them up on the internet. I specifically looked at the "405 line televisions". Which were using the original 1936 (approx) era TV signals. Ironically it was called HD (High Definition), because it had at least 220 lines of definition. In practice it had about 377 lines (interlaced, the rest were used for giving it time to move the electron beams back to the top, left, etc).
Apparently (I read), that the magnetic fields that emanate from (especially the old ancient types) large transformers (maybe a few amps needed on the primary side), which a 6.3 V filament transformer, for all the valves in an old TV, would need. May have potentially messed around with the fine control of the electron beam (fluctuating stray magnetic fields), in such an early TV. So by having one less transformer, maybe it helped improve the picture quality (
significant speculation, I could easily be wrong, there are probably other important design factors as well).
The 50 Hz field rate, because it is the same 50 Hz of the transformer, is suppose to minimize the disruption, anyway. But some distortions still get through though.
Anyway, I agree with you. Almost any solution is probably workable/reliable, as long it has been properly engineered, and proper quality/speced components are used.
I am probably biased these days against the capacitive voltage droppers. Because so many of them come from China, and are not necessarily safely, reliably designed/built and may be using sub-standard components.
Because there is so little room inside a modern light bulb, and it will probably be LED based and relatively low power/current. Using capacitive droppers in them, probably makes a lot of sense, if done properly/safely etc.
After the 10,000 or 20,000 hours lifetime, it will probably be binned, anyway. So if the dropper can reliably last, at least as long as the LED's and other circuitry, then I guess it makes sense.
It also probably helps to keep the costs down.
As long as fingers can NOT contact any live metal of the bulb (and other safety issues, including kids messing with metal objects), and it is not a fire hazard when the components fail, it should be ok.