This is an unusual experience. A huge number of people dose phosphates regularly, following the EI method, and no algae problems result. I don't know why you have had the experience you had. We do know for sure that dosing phosphates does not cause algae problems in a planted aquarium. When so many people do so, and do not get algae problems, that clearly proves that dosing phosphates does not cause algae problems.
In fact a very large number of us have found that if we dose even more phosphates than called for in the EI tables, we can greatly reduce green spot algae problems. GSA is much more difficult to handle with routine maintenance than green dust algae, because it can be extremely hard to scrape off.