The 2 month version could be sold at all, the 6 month one can't, so it's not worth considering its technical merits.
Then the client/stakeholder buys in, the sunk cost, well, sinks in, and things get fixed. Success!
In 6 months you need a better scaling version while the current version is creating cascading database failures; it's got terabytes of denormalized data that is out of sync and a 2nd team can't migrate the data in 12 months.
In 12 months, you find 5 other teams copied the 2 month solution.
In 2 years, you have 0 devs left that can solve the problem and a 1000% grown dev team that is great at the 2 month solution.
You ask the teams why they don't use the scalable solution and they say, "do we have any examples of that, the unscalable way is our convention"