Microsoft doesn't understand that Photos/Videos and Music are much better managed when stored in their own data stores and apps that are designed specifically for managing that type of media. This is why Apple has [had] iPhoto and iCloud Photos and Google has [had] Picassa and Google Photos.
Microsoft is the only one of these companies (that manage a heavily used device + services ecosystem) that is still trying to get users to manage Photos/Videos on a raw cloud storage file system - while just putting lipstick on a pig with their apps or web interfaces.
Beyond that, a 100GB Google Photos subscription is only like $1.99/mo, and iCloud is $2.99 for like 200GB.
Smartphone photos are bigger for some phones due to the devices chasing megapixels. Yes, you will eat up storage if your phone is taking 50-100MP photos and you're uploading those in full quality. However, many automatically bin down to 12MP, and those aren't super heavy - especially if the phone is taking HEIC/HEVC instead of JPEG/H.264. It's really the high resolution/high framerate video that takes up a ton of space, and this requires you to manage your storage no matter the capacity. You have to go in and delete the videos that are not keepers, instead of simply uploading every 2 second 4K "junk take" to the cloud.
You should be setting your phone to snap HEIC/HEVC instead of JPEG/H.264 - unless you use your phone for work and this causes issues (e.g. if you have to take pictures and upload them, though there is a setting on iPhones to share in JPEG format).
The same could be said for photos, but they waste less storage than the video, which really can ramp up tons of storage over a small number of files. Useless burst shorts, unsalvageable blurry or dark photos etc. You have to manage your storage.
I don't see a reason to use OneDrive over Google Photos or iCloud Photos on those devices, anyways. Those services generally work better on Android or iOS - respectively. OneDrive has issues with devices that are set to use SD Cards as camera storage, for example. You basically have to move everything to your internal storage in order to sync it to OneDrive. Google Photos doesn't have this issue.
On iOS, iCloud Photos works in the background without any issue. I feel like you absolutely have to keep OneDrive open and the phone awake or you run into issues with failed uploads, etc.
But there is very little Microsoft can do to rectify this. This is just a 1st party advantage they can't develop themselves out of, since they do not control the underlying platforms (iOS) or the distribution of Android being used by the phone manufacturer (Google, Samsung, etc.).