I do sometimes worry that these petitions are ineffective precisely because they mix issues. The question of whether there should be national ID cards is different from the question of teh #BritCard.
Even if having ID cards rather than relying on some mix of passports and driving licences was a good idea, a digital-only version is a terrible idea.
And in practice, blocking #BritCard will block any ID card system. But mixing the issues will put some people off signing.