Eh, that's also in how you define "good." High silver is like top 1/3 of the ladder so imo I'd say that's decent bc it's better than average. I'd say gold and plat are probably good imo, just not great or "damn you're good" level. I dunno, I think of it kinda like college or something, if the only people considered smart are the top 1% then we are talking PhD and MD graduates mostly, and from maybe half the schools in the country at most. Most people would say that graduating with good marks from a decent school would be worth calling smart, or that masters level work would at least count.
However, I think it might also be relative perspective. I just graduated w/ a masters from a school that is top 10 in the country for what I studied and I wouldn't call myself smart. In large part that is because when I think of "smart" people I think of the ones I sit in with and respect that are that next level (challenger academics and research tier :D lol); people whom most of population would consider brilliant. I've learned to accept that I'm smart in general terms so I don't argue with people when they say it, because it's probably true even if it's not the conception I have of the term. Similarly, as you get close to top tier play you probably start to realize how far from top tier just being good actually is. There is such a huge gap between good and great, smart and brilliant, that it becomes easy to discount the former as you approach really understanding the quality of the later. However, I think in this case a decent argument could be made that given the percentage of players who make gold/plat, they are solidly above average and that probably qualifies as good, but not great.