Why do many large companies independently develop IM instead of using software such as Nail and Enterprise WeChat?

According to the popular saying now, it is self-control, avoiding neck sticking, forming internal circulation, and fat water does not flow out.

1, data security and information confidentiality must be the primary consideration. Imagine that 10,000 people and 100,000 people in the whole company use the same communication software, and all kinds of business documents and trade secrets are easily leaked if they are not careful, such as Evergrande documents leaked some time ago.

2, and third-party software can't flexibly meet individual needs, so why not do it yourself?

Secondly, we have strong development ability, so why not do it ourselves? Maybe we accidentally hatched a new product.