In my opinion the conduct brake system that Giant uses is really nice. It's not unobvious to me that they use it to save on the costs of using full hydraulic shifters on their bikes, I was sceptical of it first.
However I think it's one of those don't knock it until you try it systems. I toyed with full hydraulic shifters and found the mechanical shifters to be more ergonomic and comfortable as they are much smaller on the hood tops, at least with the Tiagra hydraulic variant. It does also make it very easy to mix and match shifters if you want to upgrade them later down the line. I prefer the feel of the conduct braking to the Deore hydraulics on my old Talon mountain bike.
Just my observations of them, I see a lot of people bashing them and I totally understand why but I really like them. And yes I agree that proprietary systems are never nice on a bike, we want more options to customise and replace, not less.