Orthodontic extrusion or crown lengthening?

I have been told that I have a tooth with too much decay, particularly close to the gumline, and that to restore the tooth, crown lengthening will be needed.

I understand that there are a lot of disadvantages to crown lengthening, and that orthodontic extrusion has fewer downsides.  Is that true?  Can most teeth that need CL treatment be extruded instead?  Can I expect orthodontic extrusion to cost almost as much as orthodontic treatment of the entire mouth, or is it usually just a fraction of the cost?

Also, why is extrusion generally disfavored in the US (as opposed to CL) compared to overseas?