It depends on your definition of "Best". In most cases, people may associate that with expensive, full range floor standing speakers in the price range of something like $20,000 and up.
In those cases, they usually will have large, such as multiple 8" woofers, relatively large mid range drivers and have recommended amplifier power of 50 to 500 W or more. So simply by that indicator, one would naturally stay away from AVRs and integrated amps. Entry level to mid range integrated amps are often stripped down AVRs, it is hard to find one that has the juice for the likes of Focal Aria, Kanta 3-way large towers, let alone the higher models such as the Supra and Utopia.
That said, someone like me who is silly enough to use medium large towers such as my Focal Electra that dips to 3.5 ohm, recommended 40-300 W, there is no problem driving it with any AVRs such as the X3400H. In fact, I tried mine with my DIY Passlab 5 W amp and they sounded fine, sitting from about 8-9 ft.
So again, it depends on your usage, anyone who told you your AVR cannot drive your 4 ohm nominal speakers are just offering you their opinions based on their understanding. Yes it is always better to use separate power amps, all else being equal, but all else are not always equal. Unless money, space, convenience etc. are no object, each case needs to be properly assessed.