I don't agree with that. It's like saying in JavaScript the "const" -keyword is distracting because it creates a distinction between values that are constant and values that change during running the program.
The spreadsheet-app might have a "publish-mode" where the distinction between inputs and formulas is hidden but in general it helps that user can easily distinguish between between inputs and procedures.
Distinction does not imply distraction.
What is often distracting is the need to spend mental effort to make a distinction, to try to understand a spreadsheet.
You might as well say that gaslighting in general reduces distraction, because there are fewer distinctions you can make in the gas-light.
Though like you can optionally use const (for varying degres of optional depending on your local coding style rules), you can optionally highlight formulas using conditional formatting based on the ISFORMULA() function.
It does seem like something that makes sense to be a built-in though.
When needed, a visual indication can easily be created with conditional formatting, or with the Show Formulas command (Ctrl+`), as noted by the sibling. Know your tools is the answer here.