To use some simplified numbers to explain it - consider that normally 100,000 people are infected with some form of respiratory virus on a daily, basis and 20% of those are rhinoviruses, then that means there are 20,000 daily rhinovirus infections. And let's also say that strains of influenza are another 20% and 20,000/day.

Now what is happening, is in a covid world, due to masks and distancing, the number of people infected on a daily basis drops from 100,000 to 10,000. Rhinoviruses are sill 20% of that, but they are now down to 2,000. Masks and social distancing has had a drastic affect on them.

Influenza drops down to only 2% so only 200 cases daily. Masks and distancing have an even more drastic effect in influenza.

As a result, we're seeing exactly the graph you've linked.

Rhinovirus is 20% rate, but of a much smaller pie. And you're mistaking that as masks and distancing having little or no effect.