Don't confuse 'Crestron native' and 'Crestron capable'. A big issue is that things like Amazon Alexa are 100% proprietary methods of control. They are not open in any way whatsoever. Same with Google stuff. Things are built to use Alexa, but that is ALL they may happen to work with. Zigbee and Z-Wave have similar issues. They are closed protocols which make them very tough to integrate to. This is far different than devices which have open standards like Ethernet, RS232, and others. The use of closed protocols makes integration to certain devices relatively easy, but then you have to decide if you want a second layer of control, custom built, around Crestron, or if you just want to use the app that the developer spent tens of thousands of dollars on to make work really well from your phone/tablet?
There are some things which Crestron does relatively well. Control distributed audio and video is one of them. It can control your receiver easily, make sure your TV is on the right input, etc. Alexa sucks at this. But, when it comes to controlling your lights, it gets a bit murky. I'm a fan of things like what Lutron has to offer because they offer open control methods. Security can be tricky because of the... security required. But, do you really need security on a device that isn't your phone and the native app for your security system?
Things can get very expensive, very quickly, and you can end up with something very cool, but not all that practical in the real world. Or, you can get something that's not quite as cool, but is much less money, and offers just as much or more overall control.
I didn't bother integrating my Nest into my home AV system. Or my Plex server. I just control the Nest directly from the app, those few times I want to. And the Plex is controlled from Roku units, so why would I need to control it directly? My door lock? That is on my system. But, I don't stream cameras to my Crestron as I already have them on my phone in their own app.
Crestron really is capable of controlling a wide array of devices, but a bunch of newer devices are being designed without open standard protocols which they publish and this means that they are actually a very closed off product. If they were to publish their protocols, then Crestron would be more capable of controlling them. But, at some point, device selection starts to matter a great deal.