The problem with thread is that many sewers do not understand it.
There are many kinds of thread. Some threads are made of natural fibers like cotton. Some threads are made of synthetic fibers like polyester. As long as you use high quality long fiber threads, you will get a good result. It is best to match the fiber to the fabric. It is also good to consider the special characteristics of the threads.
Unfortunately, many sewers buy the cheapest threads they can find. They are all excited to find special deals like 4 spools for a dollar. The quality is expressed in the price. If it has a cheap price, expect it to be a lousy thread.
Thread and especially natural fiber threads deteriorate over time. They lose their strength, color, and stability.
Recently, a customer brought a Singer 403A for sewing machine repair. She said the threads kept breaking. There was nothing wrong with the machine. It was her thread. She was trying to use twenty year old super cheap thread. It broke without any significant tension.
Using bad threads will often lead to unnecessary sewing machine repairs.
Suggestion: Always use good quality threads that are fresh and not old. Avoid old threads. Avoid cheap threads.