DeviceTree is a massive improvement compared to no discoverablity AND no DeviceTree. Each device was a custom kernel build, duplicate drivers and other code. It was madness. Linus lost his shit with the ARM kernel devs saying it has to be sorted. DeviceTree was the solution.
In the end, ARM will have discoverablity. Buses like I2C and SPI will have some standard to discover what the hell is on them. But today it's chaos and DeviceTree is the only source or order.
You still need a way to know which memory addresses your I²C or SPI interface has. While DeviceTree is better than nothing, it's way worse than the "It just works" of ACPI
Completely agree that discoverablity is better. But that needs hardware. It's crazy this isn't solved. It means ARM devices are basically made to be e-waste. Make phones and other ARM devices like PCs. Google could mandate that hardware must be discoverable and be able to run a generic stock, to carry the Android brand.
Since the OP specified server hardware, probably not. RH said RHEL wasn’t going to support anything which didn’t use UEFI to boot, and Arm specified UEFI in their ServerReady hardware certification.