The last time that was possible was something like 100-200 years ago, before specialisation became so important.
I don’t know anything of note about pharmaceuticals or civil engineering, rhetoric or national security, trade or industry. But I think it’s a safe bet that 90% of the people on Hacker News knows far more about computers than the average UK politician.
If everyone in a nation has to learn politics well enough to govern, nobody would have time to learn anything else. The only measure by which I can even judge politicians is their character, their honesty, their morals — and I do recognise the problems with even those as my measure.