Rarely has a side had 2 or 3 outstanding bowlers and a couple of good ones in ODIs, ever. Australia for instance have had Lee, McGrath and Gillespie, all of whom you could at a stretch call outstanding, and then you could throw in Hogg who's good, but invariably you'll have some part timers filling in some overs somewhere. Even before the days of specialist ODI teams when say the West Indies picked all their quicks, they still had Richards or Harper or someone bowl a few of the remaining 10, as did all teams. The only way you could get 50 genuine quality openers from international class front-line bowlers would be to have one or two quality all-rounders, and very few teams have that option.
Australia could pick Lee, McGrath, Gillespie, Bracken and Hogg, but they aren't likely to because of a) the batting and b) the over rates. A guy like Symonds who can give you a few overs going at 5 apiece or less, bowl them quickly and then bat later is invaluable, and teams have always recognised that.
Anyway, even Australia of a couple of years ago who had 4 genuine class bowling options didn't consistently restrict teams to under 240. No teams have been able to consistently do that since the mid 90s, when ODI tactics changed dramatically and scoring rates increased.