It only targets big "platform providers" not startups. It even levels the playing field for those startups. People get so ideologically tangled that they just knee jerk.
I wish people being even that principled... I think the reactionaries in this debate are just the current generation of Apple "fanbois" who, for whatever reason, feel some need to "protect" a trillion-dollar company, or just good ol' fashioned elitism?
My pet theory is that the frothy bile in posts wanting to keep iMessage private is probably grounded in psychology/sociology: People with a quite genuine fondness for Apple's products and services, combined with their higher barriers to entry (monetary cost), forms the basis for their in-group identity, and they don't want an out-group seen as inferior (Android users, etc) from getting to join-in their, private, shared-experience. It's the same as with kids fighting over PlayStation vs Xbox.
Heh, it reminds me of when I was like that: I was a very visibly-on-the-spectrum kid who knew Photoshop, before anyone else at my school even knew what it was; when MSN Messenger 6.0 came out with support for custom user avatars/profile-pics: I thought this would lead to "normal" people learning Photoshop/digital-art and airbrushing and all getting their own Wacom tablets to make their own avatar-art and I'd lose my... special status as that one weird kid who knows Photoshop. Nah, turns out in the end everyone at school just used photos of themselves or the logos of rock bands (Radiohead's was popular) or sportswear brands. And in 2023, most people still don't know Photoshop.
So being an Apple user tends to makes someone protective of whatever they feel makes Apple... Apple. Fortunately those people aren't MEPs who get to vote on legislation with a demonstrable public benefit.