Never used Toslink. I did for awhile use either AT&T multi mode glass or Theta single mode glass, both now pretty dead. Toslink had a bad reputation in those days, and I agree with
@DonH56 about the interface circuits probably being the culprit. It was also found to be microphonic, unlike the more sophisticated glass protocols with their far better connectors, at least back then. It has survived as a cheap interconnect method, but who was or is ever going to invest in the engineering to improve a cheap, low volume interconnect method to make it really good?
I know of no provable advantages it has over spdif/AES or USB, other than the overblown ground isolation myth, usually easily curable in systems with metallic interconnects. Me? I am a very happy USB user, with no dodads or gizmos in the signal path. I just use a properly isolated DAC.