This argument is getting annoying.
Typing a couple of letters and then tapping a suggested word is not always going to be faster than typing out the entire word completely. In most cases, it will actually be slower.
There are two reasons it is actually slower, and that is because it requires looking and thinking.
We are so used to typing on our phones, we never really think about typing. We just think about the words. We don't think about where each letter is or which letter to type next. If we want to type "hello", we just type it without thinking about it. But if we want to use prediction, we type "hel", then we stop, look above the keyboard to see if "hello" is even there. At this point, our brains essentially have to calculate an if/else statement. If hello is listed, we look to see if it is the first, second, or third predicted word. And since the keyboard is always adapting to our ever changing usage, its position will not always be in the same place. Meaning we have to look to find "hello" then we have to tap on its position which will vary. However, if "hello" is not listed, we would type another "l" and run through that whole process again. And the worst part is that depending on how many letters we type, how recently we used the word, and how often we used the word (which by the way all 3 of these things are constantly changing throughout the time we use a keyboard), the position of the desired word will change. So by using this method, we are required to make a conscious effort on a single word. When in reality, I shouldn't have to. Even while typing this, I am not thinking about letters, position, or anything like that. Words just pop up in our minds and then muscle memory takes over. We don't think about the letters we type, we just type them. Having to think slows us down.
Or we could just type the word "hello" much quicker and be done with it. But whatever. You use your phone however you want.