[Moto G4 Plus Questions & Answers] echo92:
In theory that should work. However, for that tool, you'd need device and CPU specific flash files, which are not easy to find. A blankflash has them packaged together. You'd likely have to try to find MSM8939 specific flash files for Motorola devices - as far as I remember, Motorola includes special cryptographic signatures onto their flash files. Then you'd load them into the Tool for delivery to your bricked device. The files would have to be new enough that your Nougat bootloader would permit them to be flashed - older files may be rejected as a security downgrade.

You may wish to follow this thread for fellow Moto G users that have hard bricked: https://xdaforums.com/2015-moto-g/help/help-blankflash-zip-moto-g-turbo-t3674207 However, I concur with acejavelin's post that unless there's a blankflash that is leaked or a loader image, the only prospect is a motherboard replacement. You've corrupted your bootloader in such a way that it requires a special sahara communication protocol/firehose and a dedicated flash file set to repair. You can try to find or make a loader image from a working device - i.e. a full copy of a working firmware, that you load onto a SD card and hope the device loads from there. Here's an example for one from the Moto X: https://xdaforums.com/moto-x-style/help/solved-hard-brick-moto-x-style-xt1572-t3693860

As for 'are Motorola managers crazy?' I have no reason to believe they are. The warnings about risks to your device when trying to unlock aren't there for show, plus every OTA update I've spotted has the line 'You cannot downgrade to a previous version after installing this software' (e.g. for Moto G Turbo http://motorola-mobility-en-in.custhelp.com/app/answers/detail/a_id/110009 ). Though you can downgrade, attempts to use OTA updates have resulted in hard bricks - just ask Moto G4, Z Play, X, etc users, and that's just the Motorola side of things. They appear to formally disapprove of downgrading and regard as anything happening to the device with downgrading as your responsibility. I should stress this is not unique to Motorola, LG for example has incorporated rollback protection, whereby downgrading itself will formally brick your device. https://xdaforums.com/g4/general/psa-warning-try-to-downgrade-g4-t3197675

Should there have been more warning that downgrading may permanently damage your device to the point where you may have to pay for another device or expensive repairs, and Motorola absolve themselves of any responsibility? Perhaps (though the legal pages when you unlock do expressly mention that - any issues that happen when you've unlocked your bootloader are your liability. Service centres in different regions with varying levels of consumer protection laws may have a different view).

It could be argued that Motorola should release blankflashes and stock ROMs for those that do like to tinker, so that it requires fewer repairs, though I imagine the engineering and subsequent support outweighs that. Regardless, if you really want to tinker/downgrade, you may have to look at other devices/other OEMs. I imagine they're similarly stringent though, apart from OEMs like Oneplus who don't mind you unlocking your bootloader. If you really want to stick with Motorola or other OEMs, please do not blindly downgrade your stock firmware.