Same can be asked, why do some like lock-in so much that they avoid cross platform development?
The important parts of your business are in the backend, and should be accessible in json format. If you have a good api, developing native clients should be simple and fast. But what I have seen are very confident web frontend devs (and product managers too) who only consider web solutions, and dismiss native apps as being duplicated work.
In my experience the backend of most non-tech and some tech businesses is a database and some trivial validation rules. Everything important is in the design of how the data is displayed on the front end.