The utmost commonplace transaction measurement was launched in PR 2273. On this PR, the rationale is given as
Extraordinarily massive transactions with plenty of inputs can price the community
virtually as a lot to course of as they price the sender in charges.
A equally worded remark lives within the codebase as we speak above the code that performs the test.
This restrict was launched at 100 KB; when segwit was launched, it was modified to be a weight restrict modified to 400000 weight which leads to an equal 100 KB non-witness measurement restrict.
