请教一个关于代词就近指代的问题

hxh2215

Marconi conceived of the radio as a tool for private conversation that could substitute for the telephone; instead, it has become precisely the opposite, a tool for communicating with a large, public audience.

请问，这里instead后面的那个"it"为什么可以"clearly refers to the radio"？为什么不会误指离它最近的telephone? 谢谢