Why numerical concentration does not settle battlecruiser employment

Could the desire to use all available numbers explain placing battlecruisers in the battle line?

Yes, but concentrating numbers did not make battlecruisers suitable for every role, and armour comparisons must account for each navy's requirements.

Concentrating every available capital ship offers a numerical explanation for putting battlecruisers into the battle line. Numerical strength alone does not establish whether a ship suits that employment. German battlecruisers' heavier armour fitted German requirements, while British ships served a different operational purpose. A comparison based on maximum armour thickness can favour one navy's ships simply by judging both designs against that navy's requirements.