investors that have long time horizons to invest in good index funds. There shouldn't be a whole lot of advice unless someone really needs a set plan and doesn't know how to execute it. That is where a professional could come into to play. Not many people need that. There is a lot of online good advice for that.
Where professional advice can make a big impact is in the "deculumation" of assets. It's actually not that hard to save, but it's incredibly hard to wind down assets. Especially from an estate and tax standpoint.
Most investors, hopefully, save enough but they need help. Social Security, defined benefit plans, other assets, all play a significant part in the process.
Sometimes, depending on the situation does require professional advice.