It made sense in the early days when apps were $0.99 and credit cards charged approx $0.19 + 3% per transaction (Apple likely gets better rates, but just as an approximation).
There's still a lot of apps that fall in that range, but I'd agree with you that it's completely unfair for subscriptions and more expensive apps.
Steam is probably also overcharging with their 30% cut (once upon a time that was an amazing deal compared to boxed retail) and most games are $30+ so it's a pretty hefty chunk of change. I don't necessarily agree with the exclusivity tactics taken by Epic or EA/Ubisoft but having more diverse options for buying PC games is a good thing.
Steam's store page promotions provides up to 80% of the revenue for indie games. 30% is a steal for what they offer. Discord nitro offered a selection of games along with its premium subscription. People would take the subscription for the chat features and very few if any played the games offered with it, to the point where discord just cut the games out. Nobody cared.
I've spoken to a few silicon valley guys who believe steam will be disrupted, but I just don't see it at all. Epic has a chance because of fortnite users. Steam was built on hl2, epic on fortnite. Features and cut %s aren't the deciding factor.
The non-standard features like Steam multiplayer and mods Workshop that lock out non-Steam users pretty much forever are IMHO even worse than the 1-year exclusivity (as long as it's not retroactive).
Steam multiplayer? You mean the friends list? Steam doesn't provide hosted mp servers for games. Mods are made by community members that can be released anywhere. Workshop is just a distribution channel.
Battle.net and origin are lock in services. Nothing about them is open to the public or accessible. Steam is pretty open and reasonably successful at it.
Mods can be released anywhere, but in practice, usually aren't !
Steam might not provide hosted MP servers for non-Valve games (are you sure it doesn't ?), but we've even seen older games having Internet multiplayer removed to the exclusivity of Steam's own "VPN" : Dawn of War 1, Civilization 4 (for which they also managed to break most mods for no seemingly valid reason)...
In my experience they aren't different at all. Steam Workshop is just a distribution platform for mods. It's a mod installer and manager. It doesn't stop you doing it manually.
Steam doesn't host multiplayer servers, but it does offer services for match making, lobbies, voice chat and P2P networking (including the use of Valve's network as a relay).
Also, Battle.net is in a somewhat different category, as, as far as I know, is only used for Activision-BLizzard games ? (No possible monopsony issues when it's the same company !)
There's still a lot of apps that fall in that range, but I'd agree with you that it's completely unfair for subscriptions and more expensive apps.
Steam is probably also overcharging with their 30% cut (once upon a time that was an amazing deal compared to boxed retail) and most games are $30+ so it's a pretty hefty chunk of change. I don't necessarily agree with the exclusivity tactics taken by Epic or EA/Ubisoft but having more diverse options for buying PC games is a good thing.