Because it is?
I studied Russian for three years in high school (Pasadena High, CA), and spent all my time learning declensions and conjugations and endings and all sorts of things. In Chinese, a word is a word is a word.
To learn Chinese, you need to learn radically different vocabulary and a very different way of expressing things.
Mouse (computer): Russian, мышь/mysh’: Chinese, 滑鼠 huashu, slide mouse
History: Russian, История / istóriya: Chinese, 歷史 lishi
Pavilion: Russian, Павильон / pavil’yón: Chinese, 涼亭 liangting, cool pavilion
A very different way of saying things:
你早點來的話就不會淋雨。
You early bit come of talk achieve no meet soak rain:
If you come a bit earlier, you won’t get wet in the rain.
equally: If you had come earlier, you wouldn’t have gotten wet in the rain.
我看到他的時候，他剛看完牙醫，麻藥還沒退，不想跟我講話：
I see at he of time time, he just see finish tooth doctor, numb medicine return sink retreat, no think heel I talk talk:
When I saw him, he had just been to the dentist’s, and the painkiller hadn’t worn off yet, so he didn’t want to talk with me.
These are just two random examples of sentences I have used recently that popped into mind.
(這兩個例子，就是隨便舉我最近講的話，剛好想到：this two piece example thing, achieve this follow convenience I most close speak of talk, just right think at).
So you get the idea. The sentence structure is minimal, and there are no plurals or tenses to worry about, so you have to get used to it.