IIRC, there was a thriving, multi-national genre, of the 'clever loner' trumping Plod. Even Poe had a go...
The French had an infamous mega-villain, who bestrode Paris and tied pursuit in knots. Like J.Bond slaying 'double' after 'double', but always missing the *real* Blofeld...
IMHO, AC Doyle not only ticked all the boxes, he was in the right place at the right time, he had a renowned Scottish doctor as a deductive model, had the 'Strand Magazine' and an inspired illustrator...
Disclaimer: My child-hood reading included an aunt's bound issues of Strand magazine with several serialised Holmes tales...
( I was an *easy* child to mind on a wet afternoon-- Just hand me a book...

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