Today, no elite fighters are unaware of the Thai clinch, but Muay Thai is not only about clinching. Let's think about a fighter's style and how it incorporates Muay Thai.
At UFC 178, Donald Cerrone faced Eddie Alvarez in the co-main event. Alvarez had a shorter reach and his striking style relied heavily on boxing. Therefore, he needed to step in and out when striking.
Alvarez used that step-in movement well early on and he landed a high volume of punches in the clinch. He took the first round as a result, but don't forget that Cerrone had already started to punish Alvarez's body with knees.
Since Alvarez had to step forward when punching because of his reach disadvantage, Cerrone's knees worked well as counters.
In the second round, Cerrone's counterattacks with knees dealt more damage to Alvarez's body, and this damage left Alvarez unable to fight in the clinch.
When clinches did happen, Cerrone's knees stopped Alvarez from dirty boxing. When fighting from a distance, Cerrone's low kicks hurt Alvarez's leg and that slowed him down.
This made it easier for Cerrone to continuously attack Alvarez's leg. I also point out that Alvarez's step-in punches became ineffective with his leg damaged.
This fight was largely about which fighting length was better for each fighter. The competition mostly took place at a short length, and Cerrone held an advantage due to body and leg damage that allowed him to win.
Muay Thai (and kickboxing) is about creating attacks from several different lengths and finding the most preferred and successful length in order to win a fight.
Cerrone's skill at doing this showed in his fight with Alvarez. He succeeded with Muay Thai without relying entirely on the Thai clinch, but rather by relying upon other important and lesser-known parts of Muay Thai.
We should think more about how fighters try to get better at using length and angles against each other.