Absolutely. First and foremost, because having many ECs means you’re constantly jumping from one to the other, allowing only superficial involvement. Club memberships and honor societies mean little without significant participation or accomplishment on your part.
And, as Cal Newport (Study Hacks - Decoding Patterns of Success - Cal Newport) puts it, accomplishment is exponential rather than linear. Meaning, if you are heavily involved in one activity, you will be exposed to opportunities to grab “low-hanging fruit” and will end up with a list of related, impressive activities–a list so impressive that it would have been impossible to accumulate unless the awards were connected. His example was his research at Dartmouth, which earned him publication in journals, a grant to research during a summer, etc, but it holds true for high school students as well. The writer who spends hours a week on her poetry will eventually become good enough for publicaton in literary magazines, win national awards (Scholastics Art and Writing awards, for what it’s worth, do a great job of making several awards out of one piece–you can win a regional award, a national award, and publication in Best Teen Writing with one piece), become editor of his school’s lit mag, etc. The writer who is also student council secretary, French club treasurer, takes piano and saxophone lessons, and is taking an online class doesn’t have the time to garner truly impressive accomplishments.
That being said, there are those truly well-rounded individuals. NSM has mentioned a young man who was president of the national NHS and had organized several major fundraisers, alongside a slew of other, disparate activities. But these kids are rare birds, and more often than not, having multiple activities means either burnout or unimpressive involvement.
In your specific case, your many activities could leaveyour application looking cluttered an unfocused. My recommendation (as a high school senior, so take it with a grain of salt) is to pick those activities which are most meaningful to you. (CommonApp only has room for seven activities anyway.) Personally, I am leaving out superficial club memberships (French club, writing club) and activities that have no relevance to the composite my other activities form (mission trip to Costa Rica).
Best of luck!