I disagree.
The core issue of the martial/caster gap is that casters are built for long encounter days and therefore have a ton of resources. However nothing stops a caster form not metering out their resources over a long period of time and instead using all their resources in a short period of time.
Nonmagical martials tend to not have resources. They cannot become more effective in shortened days.
This is why half caster martials are rarely problematic. They have resources for longer days, they can burn faster for shorter days, but their abilities are not strong enough nor numerous enough to overwhelm shortened days.
The core issue of the martial/caster gap is that casters are built for long encounter days and therefore have a ton of resources. However nothing stops a caster form not metering out their resources over a long period of time and instead using all their resources in a short period of time.
Nonmagical martials tend to not have resources. They cannot become more effective in shortened days.
This is why half caster martials are rarely problematic. They have resources for longer days, they can burn faster for shorter days, but their abilities are not strong enough nor numerous enough to overwhelm shortened days.