Should we make app dir nested route opt in rather than opt out

[boompikachu]

I would like to suggest an opt-in nested route. I think it would help organize the folder structure more easily.

let's say we have the following:

app/
├─ layout.tsx
├─ page.tsx
├─ setting/
│  ├─ page.tsx
├─ home/
│  ├─ banner/
│  │  ├─ banner.tsx
│  │  ├─ index.ts
│  │  ├─ utils.ts
│  │  ├─ ...other files
│  ├─ some-button.tsx
│  ├─ page.tsx
│  ├─ layout.tsx
├─ [user-id]/
│  ├─ page.tsx

At first glance, user might think /banner is a nested route but in reality, it is just a component with some utils inside. We can fix it by moving into a components (or _components) folder instead but sometimes, with little components, we just want to leave it outside.

But what if we force all route to start with a specific character? (in this case an * or maybe an _)

app/
├─ layout.tsx
├─ page.tsx
├─ *setting/
│  ├─ page.tsx
├─ *home/
│  ├─ banner/
│  │  ├─ banner.tsx
│  │  ├─ index.ts
│  │  ├─ utils.ts
│  │  ├─ ...other files
│  ├─ some-button.tsx
│  ├─ page.tsx
│  ├─ layout.tsx
├─ *[user-id]/
│  ├─ page.tsx

it would highlight all the routes when navigating through the tree which, in my opinion, really helps differentiate between which folder is route groups and which is not. I also prevent us from naming all other folder with _ to opt out of nested route.

What do you think?