I have a house full of Alexa devices, mostly Alexa Shows. They are wonderful devices adding voice activation to many devices in the home. However, the only devices that are connected directly to Alexa are my Hunter ceiling fans that use WiFi and do not have Hubitat integrations. Everything else connects to and through Hubitat and the Alexa Hubitat skill allows Alexa to trigger devices within Hubitat. I set up rules within Hubitat rather than using Alexa routines.
Alexa works with many Zigbee and some WiFi devices and may eventually work with Matter. However, is does not have Z-wave capability and it does not have an elegant integration with Lutron Caseta. Thus, there is no way I am giving up my Hubitat anytime soon.
For someone who only wants a simple home automations, Alexa might work, but as has been said, it requires the Amazon Cloud and an operational Internet connection. I have my router and Hubitat hub on a UPS backup so that even if the power goes out, critical parts of my home automation system will still function. I use Ecolink Z-wave chime/sirens that have a battery backup, so I can still receive alerts even if the power is out and the Internet is offline.