其实这句话的意思是“父母是孩子最重要的老师”，“如果做得好的话，父母可以成为孩子最好的老师”。所以你说的问题的确存在。
你是辩论赛用吗？我能想到的还有：
――当前社会父母对孩子往往抱有过于功利的期望，提出不切实际的要求，打击孩子的自尊心自信心，让孩子的童年失去乐趣；所以父母不一定是最好的老师；
――很多父母忙于自己的事情忽略孩子，农村有很多留守儿童，城市也有很多只能跟老人或保姆相伴的孩子，有的甚至从幼儿园、小学就住校了。父母根本没有时间与孩子相处，怎么会是好老师。
――离婚率上升，父母离婚给孩子带来阴影，有的还在孩子面前诋毁另一半。这样的父母也不是好的老师。
In fact, this sentence means parents are the most important teachers for children. If you do well, parents can be the best teachers for children. So the problem you're saying does exist.
Are you a debate game? What I can think of is:
The current social parents tend to have overly utilitarian expectations of their children, put forward unrealistic demands, attack the self-esteem of their children, and let their children lose their childhood fun; so parents are not the best teachers.
Many parents are busy with their own things to ignore their children. There are a lot of left behind children in the countryside. There are many children in the city that can only be accompanied by old people or nannies. Some even live in kindergartens and primary schools. Parents have no time to get along with their children, so how can they be good teachers?
The divorce rate is rising, parents divorce brings shadows to their children, and others slander their other half in front of their children. Such a parent is not a good teacher, either.
您好，您可以首先明确自己的立场，比如您的立场是“父母确实是孩子人生中重要的老师，但不一定是最好的老师。
分论点1，父母跟孩子在感情上是最亲密的，他们倾向于去保护孩子。
分论点2，父母期待孩子的兴趣爱好要跟他们保持一致，这对于孩子来说可能不利于自己的成长。
分论点3， 父母容易把自己的价值观传递给孩子，而老年人的价值观可能并不能跟上时代。
分论点展开讨论即可。
<范文>
Firstly, parents know us very much. Parents give us life, and I think that
we will spend large amount of time with them. So they know our merit and demerit
in details. Meanwhile, they will help us to get rid of our demerit.
Furthermore, parents possessed many experiences. Since they are older than
us, they have experienced many things. Sometimes, they are just like our models.
And as the saying goes: Example is better than precept. So we will
unconsciously copy some of our parents' habits and styles of behavior, i.e. we
can learn many things from them.
Finally, parents will teach us everything. Since school teachers can just
teach us knowledge from the books, our parents can teach us everything. For
example, I learn knitting, cooking and makeup from my mother, while learn fixing
leaky faucet from my father. They are the persons who love me most, so they will
teach me everything without reservations.
Just as the saying goes: There is no place like home. And I think there
is no teacher like our parents. They are the best teachers in our life.
首先，家长非常了解我们。父母给了我们生活，我想我们会花很多时间和他们在一起。所以他们知道我们的优点和缺点。同时，他们将帮助我们摆脱我们的缺点。 此外，父母也有很多经验。因为他们比我们年龄大，所以他们经历了很多事情。有时候，它们就像我们的模型一样。俗话说：“榜样胜过箴言”，所以我们会不知不觉地抄袭父母的一些习惯和行为方式，也就是说，我们可以从他们身上学到很多东西。 最后，父母会教我们一切。既然学校老师可以从书本上教我们知识，我们的父母可以教会我们一切。例如，我从母亲那里学习编织、烹饪和化妆，同时学习从父亲那里修漏水的水龙头。他们是最爱我的人，所以他们会毫无保留地教我一切。 正像俗话说的：“没有地方像家一样。”我想没有像我们的父母那样的老师。他们是我们生活中最好的老师。
是最好的老师，但不一定是托福写作的最好老师啊!
您好，您可以首先明确自己的立场，比如您的立场是“父母确实是孩子人生中重要的老师，但不一定是最好的老师。
分论点1，父母跟孩子在感情上是最亲密的，他们倾向于去保护孩子。
分论点2，父母期待孩子的兴趣爱好要跟他们保持一致，这对于孩子来说可能不利于自己的成长。
分论点3， 父母容易把自己的价值观传递给孩子，而老年人的价值观可能并不能跟上时代。
分论点展开讨论即可。