Most transformers and solenoids/electromagnets are less than 2 T (two Tesla) because the saturation density isn't much higher than that for typical core materia

Most transformers and solenoids/electromagnets are less than 2 T (two Tesla) because the saturation density isn't much higher than that for typical core material. Much the same applies to electric motors. See, for instance: https://en.wikipedia.org/wiki/Saturation_%28magnetic%29 and for some easily readable background on transformers showing simple calculations for flux density: https://www.electronics-tutorials.ws/transformer/transformer-basics.html The magnets described in the article don't have ferromagnetic cores so they do not suffer from the same problem. On the other hand the technique is not really applicable to power transmission or motive power.