This is basically the entire argument summed up in one post. In the long run, if you're going to divide the clans up into tiers based on numbers of members, the method of calculation used for Sling-Stone is the only "fair" method. For the lower tiers, the Spydrone route isn't as much of a huge deal, though it did have a pretty big impact for some clans (i.e. the clans riding the lower edge of the max at 1000 tier). But for the top tier, where there is no limit on how many clan members you can have, it encourages willi-nilly recruiting without rhyme or reason in an attempt to win via sheer mass of numbers.
DE has stated before that they wanted tighter knit clans, not the huge mega-clans that have been emerging, and thus the reasoning behind dividing clans up into a max of 1000, but under a larger "alliance" umbrella. To promote the zerg rush system while encouraging the creation and formation of smaller clans is counter productive.