It clearly states this on the guide:
Schedule A – Background/Declaration (IMM 5669)
Who must fill out this application form?
This form must be completed by:
you, the principal applicant; your spouse or common-law partner (whether accompanying you to Canada or not), and
your dependent children aged 18 years or older (whether accompanying you to Canada or not).
It clearly states this on the guide:
Schedule A – Background/Declaration (IMM 5669)
Who must fill out this application form?
This form must be completed by:
you, the principal applicant; your spouse or common-law partner (whether accompanying you to Canada or not), and
your dependent children aged 18 years or older (whether accompanying you to Canada or not).
This is not the case for spousal sponsorship. Clearly if you're being sponsored by your spouse they are already a PR or citizen. It is worded like that because this same form is used for different classes of PR immigration. In other instances, a spouse is part of the application. In the case of spousal sponsorship they are not.
Only the applicant fills out the form, like Mcbeth already stated.