That’s great advice to someone 9 years later. Also, complete BS. Your personal experience is not reflective of everyone who returned to the US, and you also can’t speak on behalf of every private employer. Many ESL teachers go home to have fruitful and rewarding careers in their home country. It’s easier if you stay on the track of teaching English, but you can switch fields if you’re okay starting in an entry-level position. You can also go for additional schooling and get a Masters degree in whatever field you wish to transition into. Finally, experience is very important when applying for a job, but it’s not everything. Personality, passion and character references all go a long way as well.
Personality, passion and character won’t get you an interview. If you worked in the field prior to leaving your home country, then yes, you have a better chance of returning to your previous field.
“Better chance” does not mean “no chance.” You basically told people to not bother applying for a private sector job if they go back to the west, which is ridiculous. I forgot to mention “networking” as well. That skill is almost as important as experience itself. Who you know, and what others say about you, can get you through many doors.