What was fundamentally different about that period of time to what it is now that would stop us returning to that price point? I'd appreciate any reliable information sources to back up any comments?
Just a simple answer: Stock to flow.
After the halving Bitcoin has become a scarcer resource, and, as the above post remined us, institutions have been buying BTC like crazy.
In the past S2F has undervalued BTC a few times (market had an higher valuation than model), with a large multiple. Market has always bome back to model valuations.
On the contrary S2F has rarely overvalued the market value, and at the most the multiple was 0.5, meaning that model price has never been more than the double of the market price.
Well, now S2F model predicts a 28,000 USD price.
Hence I cannot see BTC going below 14,000 USD.
If you want to know more about stock to flow:
Stock-to-Flow Model: Modeling Bitcoin's Value with Scarcity