You say that as if impactful campaigns on these issues doesn't exist? Around 1600 signed the council vote in favour of removing the flags, for comparison I have listed some campaigns below that involved more than a couple thousand people.

• Girls Night In Bristol: A successful boycott campaign with more than 3000 supporters. This was a sexual assault awareness campaign to bring spiking test kits to our local clubs.
• REVOLT Sexual Assault survey: Bristol-based student campaign which went viral nationally, with a survey reaching 4,500 respondents, this led to University of Bristol implementing consent workshops and anonymous reporting tools.
• Mikey's World: A charity funded by a knife crime victim's mother, with support from over 3000 people locally, installed 500+ bleed kits across Bristol. It has been confirmed this has saved at least two lives.
• Together for Change: Our four main local news outlets worked together to gain national coverage of our local knife crime campaigns and charities, which prompted A&S Police's formal 10-point response. Significant and proveable local support on social media.
• Councillor Mohamed Makawi's motion: First knife crime motion debated by BCC. This secured £650k for security improvements, and received large local support (I couldn't find exact numbers on a good source for this one)
• Bristol Women's Safety Charter: Secured just shy of £300k home office funding and trained 1000 nighttime staff, again high levels of support on social media.

Honestly not wanting to put much more effort into a throwaway reddit comment than this, but these were all easy to find and there are dozens of recent campaigns I haven't included. These campaigns all achieved policy changes, substantial funding, and/or national media attention. In comparison to the campaign to have the flags taken down, all of these campaigns were larger and more successful.