On an MBR disk, the partitioning and boot data is stored in one place. If this data is overwritten or corrupted, you’re in trouble. In contrast, GPT stores multiple copies of this data across the disk, so it’s much more robust and can recover if the data is corrupted.
GPT also stores cyclic redundancy check (CRC) values to check that its data is intact. If the data is corrupted, GPT can notice the problem and attempt to recover the damaged data from another location on the disk. MBR had no way of knowing if its data was corrupted—you’d only see there was a problem when the boot process failed or your drive’s partitions vanished.