Your creative is hit or miss.
You run tests. Some ads win. Others tank. You can't tell why, or who
they won with. Every kill call is a coin flip. Two months and fifty
variations later, the learnings are in the account somewhere. Nobody
wrote them down.
Your numbers are lying to you.
Meta says it drove $10K. Google says $8K. Actual revenue: $11K. Every
platform grades its own homework. Everyone passes, but the cash in
your account says otherwise. Then you spend $1,000s/mo on
attribution platforms that only give you directional reads, and
leave you with the same questions you started with.