ADHD holds many kids back from reaching their full potential in the classroom and today especially many kids struggle with this. ADHD stands for attention deficit/hyperactivity, and this speaks for itself on what it does to kids. I believe that it is way more common now because it can be genetic and many of us are addicted to our phones. We all go on our phones for hours a day and this results in us being constantly entertained so when it is time to learn if we find it boring in any capacity we immediately want to do something else and lose attention to the task at hand. Although this may seem like a learning disorder it is not considered one because in order to be a learning disorder it must directly impact a person's reading, writing, or math.
There is a wide variety of learning disorders in the DSM-5 and all of them cause kids to struggle to learn as fast as the other kids. Some of these disorders do have cures though and there are ways around them. For example, if someone has dyslexia there is no cure, but they can acquire an individual plan to help them use certain tools to make their reading and writing easier. One of the most beneficial ways to help dyslexic people is multisensory activities in the classroom so they can get a better understanding. With proper accommodations kids with disabilities can thrive just as much as their peers.