I highly suggest having support for two reasons.
The first is that if you are paying for college in the US (which most students are, since financial aid is extremely difficult to get as an international), you’re looking at about $70,000 USD per year. The fascinating thing about universities in the US is that this cost is much the same whether you attend ranking #1 or #50. However, your experience, opportunities and earnings potential vary significantly with ranking. This fact, along with the very competitive admissions process, is why people seek support with their application.
The second reason is School fit (and financial aid). It is very important that the university you attend is the right fit for you (culturally, geographically, academically, in size, industry orientation, competitiveness, rigor). With so many universities in the US, it is very difficult to find your fit without guidance. Linked to that is financial aid - stronger applicants have a much greater chance of receiving financial aid, so Admissions support can be the best investment you’ll ever make.
As for companies, Crimson offers all sorts of candidacy building and admission support for students with different backgrounds, interests and ambitions. Students are typically paired up with a team of mentors that are experts within their subject or domain, and more often than not they have either studied at, or are current students are studying at top US or UK universities.