To run for a county office, such as Sheriff, Coroner, Treasurer, Commissioner/Constable, or School Board, as an independent, I would need 5000 verified signatures. To list a party affiliation, I would need about 36000. Based on the experience of the Libertarian Party in 2015, I might face a 60% rejection rate for signatures, meaning I would need to collect 12500, costing roughly $25000.
To keep my party listed as a "qualified party" for the next election, it would need 20% (!) of the votes cast in a statewide race.
The major parties do not need to collect that many signatures, which gives an innate funding advantage for campaigning.
And you might expect that the other major party might not run an opposition candidate for Sheriff in a county where the incumbents are heavily favored every election, but how about allowing the candidate for U.S. Senate to run unopposed? [0] What about three of the seven districts for House of Representatives? [1]
I don't tilt at windmills.
[0] https://en.wikipedia.org/wiki/United_States_Senate_election_... : "An independent candidate would have been able to challenge Sessions if at least 44,828 signatures had been submitted by June 3, 2014."
[1] https://ballotpedia.org/United_States_House_of_Representativ... : Districts 4 and 7 were completely unopposed; district 5 had only an independent challenger.