Can I season a cast iron frying pan with avocado oil? If not, why not?

Yes, you can. Avocado oil has no taste or smell, its neutral so its fine. If anything its better than olive oil and has a much higher smoking point. Olive oil isn't neutral in taste and has a low smoking point unless its light and refined. My top oil picks would be always avocado or refined coconut oils. Coconut oil is high smoking point regardless of refining or not but refining removes the taste and smell to keep it neutral.

Any oil will do, including clarified butter, and even shortening.

You can. The idea is to use an oil with a high smoke point, and avocado oil has the highest.

You just need an oil with a high smoke point. It will work fine.

The smoke point of the oil makes it undesirable.

I have always used vegetable oil until recently I saw where Flax seed oil was highly recommended. I was running low on the Omega 3 Fish oil I take daily and got a jar of Flax Seed oil capsules. 1 Capsule drained is the perfect amount for my pan.

The posts that I just saw mentioned avocado oil as an option, there are more highly recommended oil but none of the posts said you should not use it. Most just stated that due to the expense of the oil there are better alternatives.

Use Lard.

Olive oil. Avocado might do it but Olive oil is a tried and true method.

Yes, you can. It doesn't taste of avocado and it has a higher smoke point than most vegetable oils.

Yes if you don’t mind the taste of avocado. For seasoning a cast iron pan, you want a neutral oil with a high smoking point like grape seed oil or veggie oil.