The included resistor is actually a resistor, not a fuse.
When the doorbell button is pushed, the HSDB2A is bypasses itself in the doorbell circuit. (the HSDB2A is powered for this time by capacitors it has just for this purpose)
If you are not using a chime, when the button is pressed and the HSDB2A is bypassed, the circuit is a dead short which will quickly burn out the transformer. Using the resistor creates the load missing if a chime is not used. The voltage of the transformer will not effect the short condition.
This is detailed in the installation guide emphasized in red text blocks if you read it.
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Also the reason I recommend a 24VAC transformer meant for the HVAC industry is they are generally lower priced, much higher quality and much higher VA rating (the power it can deliver similar to watts) and the chimes can easily handle the small increase in voltage. By and large, the doorbell transformers you see at Home Depot and their ilk are cheap overpriced junk (cheapness is reflected in their super low VA ratings) that often do not even deliver their rated VAC and VA.