I don't think it does benefit the open web. If consumers can't get value from the web, they'll go where they can find it. That is currently native apps, which is a closed and proprietary ecosystem. This causes the market itself to shrink, which means fewer and fewer people will invest in the web [1].
Here's a good podcast episode with people from the Open Web Advocacy: https://changelog.com/jsparty/316
> I do, frankly, think that mobile Safari couldn't compete that well in an open market, just like desktop Firefox can't.
Couldn't compete isn't a justification to exploit platform control and ban competition. If Apple's so worried that Safari usage will fall off in favor of Chrome, then they can invest in Safari to make it a level playing field to keep their user base.