Companies have buildings, machines, land, vehicles and many more things of value.
Cryptocoin have no substance at all and aren't regulated so any merger should turn out a pretty scam.
Why would you want to merge two coins? It's just easier to relaunch it.
A number of reasons. Like for example, if you want the first bitcoin clone. Or an old tested blockchain. Or acommumity that has been well developed. Or the bamebrand. Or the dev team.
Many reasons why a crypto could be bought out or merged.