I venture to bet that even you don't get what people say to you 100% correct all of the time. And you are a live human. Asking a piece of silicon to do it is rather remarkable.
Every time I ask "hey Siri, set timer" it understands me. No internet connection required.
Let's wait and see how they work before crapping on everything. If it doesn't work we will have plenty of time to be negative. Why start before even trying it.
for me I wouldn't be satisfied even if siri worked 100%. many times I listen to music or an audiobook and need to stay silent. so I am very disappointed that there won't be a choice.