POn Sat, Oct 16, 2021, 10:10 AM Erik Demaine 
(*it1, *it2, *it3)  # tuple with the concatenation of three iterables
[*it1, *it2, *it3]  # list with the concatenation of three iterables
{*it1, *it2, *it3}  # set with the union of three iterables
{**dict1, **dict2, **dict3}  # dict with the combination of three dicts 

I'm +0 on the last three of these. 

But the first one is much more suggestive of a generator comprehension. I would want/expect it to be equivalent to itertools.chain(), not create a tuple.

Moreover, it is an anti-pattern to create large and indefinite sized tuples, whereas such large collections as lists, sets, and dicts are common and useful.