What's funny to me is to watch conspiracists when they try to muscle in these "examples": they forget why they needed examples in the first place. Although it's silly- I wouldn't consider it entirely unreasonable to be interested in finding steel framed construction which collapsed from a fire.
If we had no examples- what would that mean? Nothing, really- since most fires are fought, most steel-framed construction (especially truss design) has fireproofing, and most skyscrapers are not steel-framed construction like that of the Twin Towers. Furthermore, the attack of September 11th was incredibly unique- we have no similar examples with which to draw exact comparisons. We aren't looking at steel-framed buildings hit by suicidal planes, in which a significant fire ensued, and caused collapse- because the only examples we have of that specific event are from September 11th. And don't think that "it never happened before" means it never happens.
What's the point of demanding it be a skyscraper? Absolutely nothing. It has nothing to do with the specific argument whatsoever- it's not like the towers collapsed because of fire, structural damage, and skyscraper-ness. The only reason conspiracists like LastChild include that curious requirement is so that they can avoid the examples that do fit that have already been provided for them.