your link was to an informative but still sloppily written article and in this context, your summary of the article isn't clarifying.

to write clearly, people gotta stop throwing around the word localhost because at the level of n.n.n.n there are no names, only numerical addresses and localhost is a name, one defined in a text file: 127.0.0.1 points to, not localhost, but to the local host, always; localhost (the name) points to 127.0.0.1 iff it is defined to (which should be all the time).

what I learned from the article is that a local host server listening on 0.0.0.0 will listen to everthing it can hear. But the question context here is, where will a packet sent to 0.0.0.0 go?

The point that 0.0.0.0 is not routable does not answer the question because 127.0.0.1 is also not routable; however, 127.0.0.1 will arrive someplace, at the local host. The question is whether 0.0.0.0 will also arrive into "the pool o' packets", that place that packets arrive on the local host prior to their disposition being determined (a. routed out of the local tcp/ip pool o' packets, b. listened to within the local tcp/ip pool o' packets, or c. dropped on the floor) because routing isn't only what Routers do, it's what tcp/ip does within a local host. (and btw, the article also describes that 0.0.0.0 means the default routing of last resort address in the context of a route address, also not the same as a packet destination address)