Not saying he does solo top tiers with speed. In fact, its already established that ninja do not just recklessly charge into their opponent at top speed because you will not be able to see their counter. Lee first stated this in part 1, minato as well says the same in kakashi gaiden. Probably why he relies on ftg more, cuz its safer (and faster of course).
When minato told kakashi the risk of his chidori, its quite plausible that he was talking from his own experience. Since he would know. Also when minato fought Ay, the same thing happened. Ay charged in full speed yet didnt see minatos counter, and that was before kakashi invented chidori. So it all ties in when you think about it, kakashis full speed chidori was no different to ays full speed lightning punch, which minato countered, the same way that rock jonin was about to counter kakashi.
I kind of agree, but don't compare Kakashi and Ay not seeing the counter isn't a problem for Ay, because lightning armor protects him from counter attacks which he proved against Sasuke. Sasuke ducked under his elbow and countered him and it barely scratched him.