 You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
Adjusting all my contact points to give exactly the same setup as my previous bike would make the exercise pointless (for me).
I'd agree. Bike fitting to transfer or compare fits (seat over BB, or full contact point triangle) between bikes is largely pointless imo unless both bikes also have same wheelbase and potential F-R weight distribution, handling needs, etc.
Road bike fitting guides may work as all road bikes used to be 73/73, square frame ST:TT ratios, or very close to. That all goes out of the window for MTBs and other off-road bikes. I adapt my fit to the bike's handling needs as well as ride efficiency or comfort/balance needs - that's why it's complex, there's no formulas that really work and where my 'bike fitting formulas are BS' angle comes from. Some very good bike fitters work w/o formulas.
Bike fit and bike handling are linked and it's either something you don't need to care about or it needs experimentation and interpretation to get the balance right. It's a big topic with few reliable rules, as you're appreciating : )