Anyone with company stock grants, investments, or unusual scenarios is going to find it difficult to file their tax correctly without an accountant or software. The US tax code is too complex for a regular person.
I personally used TurboTax the first few years I had RSU and ESPP income to report (and ran the end result by an accountant) but eventually switched to filling out the forms manually because I found it easier than entering the same information into TurboTax. Tax prep software is great for when your taxable circumstances change and you don't even know which forms you need to fill out, but I didn't find that it let me skip understanding the relevant parts of the tax code and I got to the point where I was having to generate preview pdfs look over exactly what it was generating to make sure I'd entered numbers into the correct spot in the software.
Filing a DIY tax return with investments is intimidating at first, but it's really not hard once you've done it the first time. Assuming you're not doing any esoteric cost basis adjustments, it's just a matter of knowing where to copy the numbers from your consolidated 1099. Interest and dividends go right onto your 1040. Realized capital gains go on Schedule D. If you hold any foreign stock, claim your foreign tax credit on Schedule 3. Investments in IRAs, HSAs, and 401(k) accounts are, of course, not reported at all.
Depends, some states (hello, California!) tax your HSA gains.
I choose to use software to make it easy. I don't feel like it's being forced since I could use paper if I wanted to. Indo understand that the tax prep lobby generally doesn't want simpler taxes or simpler filing, but it still feels way less coercive than many other areas of legal life.