Technically half true, they share the processing load of guessing the next valid block, and then share the profit when the one piece of hardware finally guessed it.
Those were the bad old days. There are pools now, like the old Seti@Home program. If your mining pool wins you get the percentage of the reward relative to the hashes you tried.
You can try to go it alone but your chances of finding the block reward are incomprehensibly low.
Network shares the load but winner takes it all, i thought.