But the problems that make estimation useless are problems that only surface after detailed digging that takes time and cross-team communication not realistically possible in time-boxed spike tickets, involving happening onto things that were not known and could not be known within a short spike timeframe.
Spike tickets are just an Agile bureaucracy thing to paper over the fact that estimation is intrinsically problematic to some fundamental aspects of one-size-fits-all methodologies like Agile.
Essentially for a spike ticket to be helpful in the common case, you need a spike ticket that just says, “actually go and complete the whole task you’re trying to estimate and then come back and tell us how long it really took.”