It doesn’t need to be biodegradable the roots will push right through them without issue… they can exert more than 100psi of pressure and thats probably understated by 50-100%. Its just plain and simple not a factor and is 100% myth. As with any observation its only as accurate as the knowledge of the person observing. I hazard a guess that in those instances the plants were very unhealthy and even then i dont see it as possible. Many blame issues
or make conclusions with little knowledge
or understanding and are bias so much so that they refuse be the reason for the poor results and it must be something else.
Im bot trying to be argumentative, just trying to make sure those reading are getting factual and reliable information as thats one of the goals of this community