What do you mean that China had a similar reduction of economy? China lost only men and material, Vietnam lost men, material, infrastructure, adobes, factories, livestock - how can the reduction of economy be similar? how can these be insignificant to vietnam? As history had shown, the nation where the battle was fought always suffers more.
I don't think it matters that if Vietnam can still resist other nations, or did not leave Cambodia. that is meaningless, as saying that China won because China still have a larger army; or that since China can still invade Vietnam, China won. So what if Vietnam can still resist another armed incursion or stayed in Cambodia? History had shown that the Vietnamese economy stagnated because of this. The fact is, China forced Vietnam into a North Korea situation, for her ability to resist an invasion, Vietnam had to feed a massive army and neglect her economy.
The fact is, the mutual defense agreement between Vietnam and USSR went out the window; - or effectively useless. The fact became that Vietnam had to spend her meager national wealth almost entirely on defense to prevent destruction by China meant that the economy cannot grow.
So yes, Vietnam did lose a lot, especially in terms of economy and opportunities.
