I think they’re great for giving OEMs extra incentive to ensure that Linux runs well on the hardware and providing consumers a slightly cheaper option. If I knew I wasn’t going to need Windows at all, I’d definitely go the Ubuntu route, but there’s software I use that doesn’t run on WINE, so I’d personally be more inclined to get a laptop with a Windows license bundled in.
I assume you’re not using iMessage anyway then because Apple’s Messages stack isn’t open source. If you’re not using iMessage anyway, it shouldn’t matter to you what Beeper Mini is doing. This app isn’t for the ultra paranoid. Neither is Google’s RCS in Google Messages. This is where Signal and Matrix would be better choices. If you are using iMessage on an Apple device, you’re choosing to trust Apple despite their app being closed source and you’re not choosing to trust Beeper, which is fine and I don’t judge you at all for that stance. But at that point, your qualms aren’t simply about Beeper Mini being closed source, the implication is that you don’t trust Beeper as a company and/or its developers which, again, is a valid stance even if it’s one I don’t share.
But I am personally pretty sure I can trust Beeper and Apple enough with my relatively meaningless conversations.