StrongTowns is constantly telling everyone "you should densify" and "you should slow down / tear up all of your streets" and "chase growth / YIMBY everything" and "hyper-invest in Downtown, only dense neighborhoods matter, middle-class housing is a worthless drain on all of society" - https://www.strongtowns.org/journal/2017/1/10/poor-neighborh...
So Carmel does all of that, tearing out intersections for roundabouts, creating bike lanes and dedicated paths, densifying everything, and more-or-less following exactly what StrongTowns is constantly recommending.
But it turns out actually following the StrongTowns wishlist is really expensive, far more expensive than not doing any of it. Now StrongTowns wants to complain that Carmel has a high debt load. If they think that debt isn't worth it, they should stop telling cities to do all of this StrongTowns stuff in the first place.
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The blog even complains that Carmel built "a New Urbanist downtown out of thin air", but does not acknowledge that this exists precisely because StrongTowns demanded it. StrongTowns is one of many New Urbanist groups making those sorts of demands on cities in the first place.