First, this is user-to-user site, so we are all users here......just like you. None of us can speak for Apple.
"Why" questions about Apple's design and marketing decisions can only be answered by Apple....and they are not here.
For what it's worth though, Apple does manufacture iPhones with 2 SIM card capabilities, but these models are only offered for sale in mainland China, Hong Kong and Macau.
I'm not recommending that you buy from a dealer in China, but that is an option if you understand both the upsides and downsides of doing something like this.
Personally, I far prefer eSIM to physical SIM cards, especially for international travel, but some folks like to do things the old fashioned way, which is understandable.