One of the main attributes of thermite reaction is? Heat. Lot's of heat. If heat of common fire weakened the structure imagine how much a thermite reaction would help!
I can see you haven't tried. Heat needs to be applied to the structural components. Thermite tends to burn through things and drain away, dissipating the heat in doing so. Nobody has come up with a viable means of cutting a vertical structural member with thermite that doesn't require some mechanism very much larger than that member; one method was suggested in 2005 IIRC involving a large ceramic device to cut a small steel rod, but scaling it up to the WTC towers, even if possible, would require several tons of hardware to be placed in the public areas of the buildings.
You seem to think it's trivially obvious how thermite was used to weaken the structure. It isn't, and whenever a truther tries to suggest a method, they come up with something laughably absurd. Please feel free to try and do better, but remember, you have to suggest a possibility. Just handwaving and saying "it was thermite" is an appeal to magic.
Oh and by the way nanothermite does exist
Development of Nanothermite Composites with Variable Electrostatic Discharge Ignition Thresholds
Maybe the term is misused by truthers, but shouldn't be made fun of and further misused by debunkers.
It shoud be made fun of, for two reasons. Firstly, nanothermite burns even faster than thermite, and would be even less capable of producing the high temperatures in the rubble pile months after the collapses that your more geometrically literate brethren so frequently advance as evidence of thermite. Secondly, due to the well-known effect by which aluminium forms a surface oxide layer, nanothermite contains a much higher ratio of aluminium oxide to metallic aluminium than larger-grained formulations, and has therefore typically only about 40% of the energy density of thermite; it's even less capable of causing thermal damage.
If you want to cause severe thermal damage to a structure, you're better off with something having a higher energy density. Kerosene, paper, wood and suchlike have typically about ten times the energy density of thermite, and they release that energy at a temperature low enough that they won't melt through anything holding them in place.
Dave