You kind of answered the question. If a part ever stops working you only have to replace that one part (amp, turntable, tuner). In your case you had to get a whole new setup. An added benefit to building a system is that you can add to it (CD, tape, Bluetooth) and pretty much have full compatibility.

None

None as you have an amplifier already, and you don’t seem bothered with the radio.

Just get a nice, used tuner. A receiver would only benefit you, if you were to add a tv and some type of video source.

…and tuners, even nice ones, are dirt cheap if you ever needed one…

I produce an FM radio program, so am biased toward radio :-) That, and I enjoy listening to CBC Radio, no matter where I am in Canada.

Take the example of separates for a tube setup.

3x the space, power consumption, cabling, complexity, expense, heat, maintenance and devices to manipulate.

The cost of tube replacement can go up quite a bit, with each having their own tube rectifiers abd power supplies, etc.

Try out a tube receiver that has a tube pre abd tuner if you want one of the greatest joys in audio. Especially voices, such as talk shows or vocal heavy music.

That’s a huge difference in investment, running costs and potential for failure.

All that said, I have systems that are separates and also integrateds that I will never willingly part with.

On the flip side the extra expense brings modularity, focused efforts on individual components, and potentially higher performance. (because of both space/design constraints like shared power supplies, potential noise, crosstalk, etc., for integrateds)